In Spain the most popular "muletilla" is "vale", it is similar to "OK", some people, in a regular conversation can repeat more than ten times this filler word. Which is your "muletilla" ?
In English I dislike 'like' being used as a filler word, although I might be guilty of it. I think it started in the US but it's common to hear here now too.
i think though just saying 'um ' is what I say most often.
Good question! I'd be interested to hear from French speakers since I'm not aware of what the fillers are.
you know
like
um