It is just those rummy apps in which you can play the Tiger vs Dragon game that will give you ₹50 bonus, ₹51 bonus or ₹40 bonus on sign-up. So this only specifies the amount of bonus that you will be getting when you finally download the apk and register on it.
But you should also know that not all dragon vs tiger game apps allow you to use the bonus in the game. Some apps need you to deposit some amount before you can actually play any game at all.
