Meaning of “bet” - Learner’s Dictionary

bet

verb [ I, T ] uk us /bet/ (present participle betting, past tense and past participle bet)

to risk money on the result of a game, competition, etc:

He lost all his money betting on horses.
[ + two objects + (that) ] I bet him a dollar that I was right.
I bet informal

B1 something that you say to show that you believe that something is true or will happen:

[ + (that) ] I bet that he's forgotten my birthday again.
You bet! mainly US informal

used to say that you will do something with enthusiasm:

"Are you going to Pam's party?" "You bet!"

(Definition of “bet verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)