What is the meaning of “you bet!”?
It means that some is sure of what they say, that they are (figuratively) ready to bet on it. The New Oxford American Dictionary has:
you bet: (informal) you may be sure; certainly: “Would you like this piece of pie?” — “You bet!”
Informally, it means enthusiastic agreement with a premise or question.
Do you think you can find a home for this puppy? -- You bet!