My faces won't fill ( Blender 2.9) Working on a human character and when i try to add faces to attach the body it wouldn't work .. Tried F , Alt + F. Relatively new to blender.
Also tried on a basic cube still won't fill in faces.
I can see you have 2 objects, because there are 2 origins.
First Join objects (cmd/ctrl + J).
And yes, Joonas is right you have doubles (&gt; Merge by distance).