To set the Field Level Security, check the below link

https://www.infallibletechie.com/2015/07/how-to-set-field-level-security-in.html

Field Level Security(FLS) in Salesforce restricts access in below

1. Record Detail page

2. Record Edit page

3. Related List

4. Search Result

5. Reports

6. List view

Field Level Security(FLS) in Salesforce options are

1. Hidden

2. Read Only

Cheers!!!