Your screenshot, while showing the problem, probably doesn't show its cause. One unlikely possibility is that you've applied those keywords by holding down Alt and using a number - this applies keywords from the Keyword Set, the grid of 9 items. But I doubt that's happening.
Do an Import and look at the right hand side of the Import dialog. I wouldn't be at all surprised if you were applying a metadata template/preset which includes keywords. Also look at the Metadata panel - have you been applying presets here?