With this restriction field you can display (or not) a field based on another field's value, e.g. when user selected Female as sex, hide field with male sizes in content view. More detailed description is available at
https://www.seblod.com/store/extensions/19160
Take note that field does not have any value before form is saved, so in form this would only work for editing, when creating new item you need to use conditionals.