The symbol of the frog is the game's wildness, but he just jumped out on the 2nd and 4th rollers. When he appears, he can replace all other symbols except Scatter. Scatter appears on reels 3, 4 and 5 and is represented by a square symbol bearing the name of the game.
This makes it easy for you to see it immediately when you win. As stated in the payment form, you can get 2, 3, 4 or 5 types in one rotation, so the potential for winning combinations is endless.