"Cleaning" does not always mean removal, although some files will be totally removed.
But it also happens that CCleaner will delete/remove certain files to clear the data they contain, and then the operating system will immediately recreate them as empty files of the same size.
So the junk has been cleaned out but the file is still there and still the same size taking up the same space.
Or to put it another way the space has been emptied, or the space 'saved' so you can use it again, but the container for that space is still there and still the same size.
Think of it like emptying a drawer full (or even only half full) of old letters - the rubish has gone and the space can be used again, but the drawer is still there and still taking up the same space.
Iit's now just waiting to be filled up with more letters again (until next time you empty it).