Hi Lucky,

You can refer the below wiki link for this:-

Using Access Control Rules - ServiceNow Wiki 

ACL rule types

Generally when you want to restrict access to certain records/ fields, you can define an ACL for the role/group and also type of action that you want to control for it say read, write, delete etc.

Also note that any ACL on the parent table will reflect on the child table as well. You can define ACL's at table level or field level. If you have multiple ACL's on the same table, its is evaluated in specific manner (field level ACLs gets prioritized over table level ACL's etc).

If my answer solved your issue, please mark my answer as ✅ Correct & 👍Helpful based on the Impact.

Regards,

Vishakha