That’s québécois for “shut up!” or “shut your mouth!”
The expression ta yeule! is a variant of ta gueule!, which means the same thing.
Both are shortened forms of ferme ta yeule! and ferme ta gueule!, which are also used.
By the way, 514 (on his shirt too) is one of Montréal’s telephone area codes.
The area code 514 is symbolic of Montréal.