What do these stars mean?

Question

What do the stars underneath my heroes pictures indicate?

Answer 1

The stars, named in-game as "star rating" tell how upgraded your hero is. Note that this isn't necessarily correlated to your hero's level. You can upgrade a hero's star rating by collecting hero tokens for that specific hero.

Upgrading Heroes involve the increase of its basic stats like HP, attack, defense and its general toughness in dungeon fights and PvP raids. This is done by collecting hero tokens found in specific dungeon levels as a possible reward from the boss treasure chest.

...By collecting enough of a specific type of Hero token, the adventurer can unlock new heroes and even upgrade its star rating.

...Once there's enough tokens collected, an option to upgrade the Hero is available in its profile tab. Clicking on it will raise the upgrade threshold to the next level. It is free to upgrade, and its stats will be improved across the board.

^{Souce: Upgrading Heroes, Dungeon Boss Wiki}