This is the 3977th most frequent French word.
bouche
Mouth.
The word 'bouche' is used here to name the anatomical part involved in singing.
Elle ouvre sa bouche pour chanter.
She opens her mouth to sing.
In this sentence, 'bouche' refers to the outlet or opening where the river meets the sea.
La rivière a sa bouche près de la mer.
The river has its mouth close to the sea.
Here, 'bouche' is metaphorically used to imply keeping silent or not speaking about something.