Hi @nitishgoyalstar! Steemit earnings are a direct reflection of your reputation score. Every time you earn a penny on the blockchain - it gives you a tiny fraction more reputation. Once you reach the next point - you will see your rep number change.
Each point you earn get's doubly as hard as the last. For example - jumping from 25-26 won't take much earning, but then getting from 26 to 27 will be a little harder... and so on.
I hope that helps!