What is the context? It's hard to tell what exactly it is referring to without knowing what the context is. I'm assuming it means that the person who is applying for whatever this is, has managed others in a number of projects, thus showing that they, the applicant, exemplify competency in whatever way they are supposed to have competency in.

I sympathise - I think what you have here is bureaucratese rather than English. The first problem, as you say, is that the structure is ambiguous -- who is practising, and does the "in a number of projects" attach to "others" or "element"? Then "competence element", which if we understood it might help us disambiguate, is not a recognisable term to most of us. The 'default" rule in English is that modifiers attach to the most recent possible antecedent, which here would be "others" for "practising" and "element" for "in .. projects", but that doesn't seem to make a lot of sense. My best guess is something like what Jake said, i.e., the candidate has done whatever it is they are supposed to know about while managing other people.

I agree with Jake, you really need a context, but it does seem to be a description of the person, he or she, who has managed others. 'practising the competence element' though, is an overly formal and rather odd way to say he is competent.