Can anyone help me with how to use the view access field

What doe the value represent?

Is it a value which relates to the User Group ID so for eaxample if I put a 4 into the view access field . It would only allow the relevant access permissions to anyone within a specific group of which the group ID is 4?

Does it work in the front end or the back end ?

Exactly. And it works everywhere, even when you call yours datas through the model anywhere in your component.

This access level ONLY relate on VIEWING the item. Nothing more (no edition specific ACL, or else)