You can level up by filling your XP (experience) bar. Every time you make a bet and spin, you'll gain XP. The higher your bet is, the more XP you'll get.
You can earn extra coins and VIP points as you level up. Below are the rewards that you might be able to collect:
Higher Max Bet - depending on your level, your maximum bet increases.
New Rewards Level - additional % Bonus Credits on all purchases.
New Feature - unlock new features in the game.
New Machine - new slot machines are unlocked.
Coin Rewards - the amount of coin rewards you get will increase as you level up.