French Perfective Aspect
The perfective aspect indicates an action, event or state that was, is, or will be complete ("perfect"), in the past, present or future. It describes a situation that takes place within a single undivided moment. The duration of that moment and its internal temporal structure are irrelevant.
When you say J'ai lu ce livre (= I've read that book), you're simply expressing that the reading occurred without saying anything about that process or how long it took.
Nous avons mangé ensemble. = We've eaten together.
Mon frère a visité Madrid deux fois. = My brother has visited Madrid twice.
Elles ne m'ont pas dit qui avait mangé la glace. = They didn't tell me who had eaten the ice cream.