I have a deep cut on my leg and inside it i can see a layer of yellow bumps and i think it's fat, what could it be?

See k nelp: If your cut is so deep it is going to your muscle you should have an expert perform first aid. The area needs to be cleaned after the bleeding has stopped. Depending on the circumstances sometimes it is a dirty wound and it needs to be cleaned and covered if it will be exposed to dirt. If it is not a dirty wound it may make sense to get the laceration sutured. Without seeing it we can not guess.