This is the 1979th most frequent French word.
tranche
Slice.
Here, 'tranche' is used to mean a 'slice,' commonly utilized with food items such as bread, cheese, or meat.
Je voudrais une tranche de pain.
I would like a slice of bread.
In this context, 'tranche' refers to a 'section' or 'portion' of something, like a time period or thematic division.
Nous avons étudié une tranche de l'histoire française.
We have studied a section of French history.
This usage of 'tranche' designates the 'edge' or 'side,' often referring to the physical edges of objects, such as books.