What is a Youtube Channel?
A Youtube channel is like an user's profile on Youtube, except that a single Youtube user may have multiple Youtube channels. When an user posts a video on Youtube, they don't post the video to their account, they post the video to one of their channels. Consequently, on Youtube, in order to subscribe to an user's posts, you don't follow the user, you follow a channel that that user owns.
Everyone who has a Youtube account has a Youtube channel even if they don't upload any videos to it. Your Youtube channel also has other things in it, such as public playlists that you created.