have it in you to do something

Từ điển Oxford Advanced Learner 8th

have it ˈin you (to do sth) idiom
(informal)to be capable of doing sth
•Everyone thinks he has it in him to produce a literary classic.
•You were great. I didn't know you had it in you.
•You spoke really well at that meeting, standing up for us all. I never knew you had it in you.
Main entry: ↑have_idiom