maîtriser

/mɛ.tʁi.ze/
1.
verbInf1stPres

to master (a skill or subject)

to be proficient in

to have command of

Il commence à bien maîtriser le logiciel.

He's starting to get the hang of the software.

2.
verbInf1stPres

to control

to restrain

to keep in check

Elle a du mal à maîtriser sa colère.

She has a hard time controlling her anger.