Read the dictionary definition of bet. All definitions for this word.
1. the act of gambling
1. he did it on a bet
2. the money risked on a gamble
3. have faith or confidence in
1. you can count on me to help you any time
2. Look to your friends for support
3. You can bet on that!
4. Depend on your family in times of crisis
4. maintain with or as if with a bet
1. I bet she will be there!
5. stake on the outcome of an issue
1. I bet $100 on that new horse
2. She played all her money on the dark horse
See also: Merriam-Webster definition of bet