A person who plays football or who is skilled in the game of football.
From 'football' (foot + ball) combined with '-ist' (a suffix denoting a person involved in an activity, as in 'cyclist' or 'guitarist').
The '-ist' suffix lets English turn any noun into a person who does or advocates for that thing, which is why we have 'cyclists', 'pianists', 'feminists'—it's one of our most productive ways of creating occupational terms.
Complete word intelligence in one call. Free tier — 50 lookups/day.