helicoptero de comba please bear in mind that this is an English-language forum, so your posts should be in English.
You may want to provide more detail about your game for instance is the player using a projectile weapon to shoot an enemy, or using a sword for an attack? The more information you provide, the more likely people will be able to help you with what you're after.
The simplest way to trigger something when an object has been hit is to use the "On Collision With" condition - so Player on collision with enemy, do X. You can see this in Event 4 of the Ghost Shooter tutorial project, where a bullet hits a monster to cause damage.
If you want a bit more control, you can use a separate, invisible sprite to act as a hitbox and connect it to the player using various methods like hierarchies, the pin behavior or manually setting the hitbox's position like in our Monk Fight example.
Ultimately, it depends on what your game is and how you're setting it up.