I'm making a character for a video game and when I try to smooth out the shading and use a subdivision so the mesh has a higher quality, this is what results:
I'm just getting started with Blender, so I have no idea what's going on.
You have several problems with your model. I disabled the Mirror Modifier and can clearly see that it is used incorrectly. You need a half part of a model but in your case it's partially half/full which will never work. Remove the entire half and make sure the origin is on the farthest right side of the model. You've got some missing polygons as well and the topology is poorly made. I recommend you go through a few tutorials first before trying to model your humanoid. Like the Donut Tutorial.