sert

/sɛʁ/servir
1.
verbInd3rdPresSing3

is used for

serves to

Ce bouton sert à couper le son.

This button is used to mute the sound.

2.
verbInd3rdPresSing3

serves (food or drinks)

waits on/attends to customers

Il sert les clients en terrasse.

He serves the customers on the terrace.

3.
verbInd3rdPresSing3

acts as

serves as

Cette boîte sert de rangement pour les câbles.

This box serves as storage for the cables.