Hi @suuriyas 

Could you please try this script:

(function executeRule(current, previous /*null when async*/ ) {

    var mvrs = JSON.parse(current.variables.sla_configuration);
    var i = 0;
    while (i < mvrs.length) {

        var name = mvrs[i].name + '';
        var type = mvrs[i].type + '';
        var target = mvrs[i].target + '';
        var table = mvrs[i].collection + '';
        var flow = mvrs[i].flow + '';
        var vendor = mvrs[i].vendor + '';
        var service = mvrs[i].service_commitment + '';
        var timezonesource = mvrs[i].timezone_source + '';
        var logging = mvrs[i].enable_logging + '';
        var active = mvrs[i].active + '';
        var durationtype = mvrs[i].duration_type + '';
        var relativeduration = mvrs[i].relative_duration_works_on + '';
        var duration = mvrs[i].duration + '';
        var schedulesource = mvrs[i].schedule_source + '';
        var schedulesourcefield = mvrs[i].schedule_source_field + '';
        var schedule = mvrs[i].schedule + '';
        var timezone = mvrs[i].timezone + '';
        var startcondition = mvrs[i].start_condition + '';
        var retroactive = mvrs[i].retroactive + '';
        var retroactivepause = mvrs[i].retroactive_pause + '';
        var startto = mvrs[i].set_start_to + '';
        var whentocancel = mvrs[i].when_to_cancel + '';
        var cancelcondition = mvrs[i].cancel_condition + '';
        var pausecondition = mvrs[i].pause_condition + '';
        var toresume = mvrs[i].when_to_resume + '';
        var resumecondition = mvrs[i].resume_condition + '';
        var stopcondition = mvrs[i].stop_condition + '';
        var resetcondition = mvrs[i].reset_condition + '';
        var resetaction = mvrs[i].reset_action + '';
        
        var tablename = '';
        if (table) {
            var tbl = new GlideRecord('sys_db_object');
            if (tbl.get(table)) {
                tablename = tbl.name.toString();
            }
        }

        // --- FIX STARTS HERE ---
        var glideDur = '';
        if (duration) {
            // 1. Convert string to integer
            // 2. Multiply by 1000 to get milliseconds (Assumes input is Seconds)
            // 3. Create GlideDuration object
            // 4. Get the internal string format (1970-01-01 HH:mm:ss)
            var gd = new GlideDuration(parseInt(duration, 10) * 1000);
            glideDur = gd.getValue();
        }
        // --- FIX ENDS HERE ---

        try {
            var r = new sn_ws.RESTMessageV2('SLA Creation', 'Post');
            r.setStringParameter('name', name);
            r.setStringParameter('type', type);
            r.setStringParameter('target', target);
            r.setStringParameter('collection', tablename);
            r.setStringParameter('flow', flow);
            r.setStringParameter('vendor', vendor);
            r.setStringParameter('timezone_source', timezonesource);
            r.setStringParameterNoEscape('reset_condition', resetcondition);
            r.setStringParameterNoEscape('timezone', timezone);
            
            // Send the formatted duration string
            r.setStringParameterNoEscape('duration', glideDur);
            
            r.setStringParameterNoEscape('active', active);
            r.setStringParameterNoEscape('enable_logging', logging);
            r.setStringParameterNoEscape('start_condition', startcondition);
            r.setStringParameterNoEscape('schedule', schedule);
            r.setStringParameterNoEscape('stop_condition', stopcondition);
            r.setStringParameterNoEscape('schedule_source', schedulesource);
            r.setStringParameterNoEscape('set_start_to', startto);
            r.setStringParameterNoEscape('resume_condition', resumecondition);
            r.setStringParameterNoEscape('pause_condition', pausecondition);
            r.setStringParameterNoEscape('duration_type', durationtype);
            r.setStringParameterNoEscape('retroactive_pause', retroactivepause);
            r.setStringParameterNoEscape('cancel_condition', cancelcondition);
            r.setStringParameterNoEscape('service_commitment', service);
            r.setStringParameterNoEscape('when_to_resume', toresume);
            r.setStringParameterNoEscape('reset_action', resetaction);
            r.setStringParameterNoEscape('when_to_cancel', whentocancel);
            r.setStringParameterNoEscape('relative_duration_works_on', relativeduration);
            r.setStringParameterNoEscape('schedule_source_field', schedulesourcefield);
            r.setStringParameterNoEscape('retroactive', retroactive);

            var response = r.execute();
            var responseBody = response.getBody();
            var httpStatus = response.getStatusCode();
            
            gs.info('DEBUG response for row' + (i + 1) + '>' + httpStatus + ' > ' + responseBody);
        } catch (ex) {
            var message = ex.message;
            gs.error('DEBUG SLA Creation BR Error: ' + message);
        }
        i++;
    }

})(current, previous);

Note: Please Mark this Helpful and Accepted Solution. If this Helps you to understand. This will help both the community and me..
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Thanks & Regards 
Deepak Sharma