In this context it means "Anytime!", showing that the speaker gladly did the other person a favor. (Thanks to @Matt in the comment who pointed this out, my first explanation was a bit misleading.) It is often used to mean "Of course!" and can be used in many different contexts. It expresses that the speaker is so confident about what they are doing that you could bet money on them doing it. "Can you do this?" "You bet!" ("Of course I can do it!") "Does anyone want ice cream?" "You bet!" ("Of course! I love ice-cream.") "Are you sure about this?" "You bet!" ("Of course I am sure about this.")

Yep, just a simple expression one might use interchangeably meaning basically "you're welcome." you bet sure thing no problem anytime of course gladly To comment on the guys above, it may just be a dialect thing. I am from the US and can attest that "you bet" is often used by myself and others.