Hi @rmaroti , 

Add toString()

updated code. its working for me well. 

checkCondition();

function checkCondition() {
    var user = new GlideRecord('sys_user');
    user.get(gs.getUserID());

    // Define the allowed countries
    var allowedCountries = ["Argentina", "Brazil", "Colombia", "Mexico"];

    // Check if the user's country is in the allowed list
    if (user.isValidRecord() && allowedCountries.includes(user.location.country.toString())) {
        // User's country is allowed, so return true to grant access
        return true;
    } else {
        // User's country is not allowed, so return false to deny access
        return false;
    }
}

🙂