In some games, it controls the rate at which experience points are earned, or the amount needed to level up.
For the first 19 levels, a character is given gold every time they level up to help them out.
There are also experience points, which level up the player.
This experience is used to "level up" the units and makes them stronger.
In order to level up players must kill monsters to gain experience points.
As you level up, the reward for completing a run will be worth more.
Some Monsters may not be able to level up at all.
If you want to level up a skill, simply do that thing.
These differences make leveling up in the game very different.
If you level up your movement bonus, that makes things easier.