Student or Learner
Does the term 'on the pitch' mean something? Is it an idiom?
Without context, I would tend to agree that it means the field of play. Could you provide context?
At a guess, I would say: Huhh you're on my pitch, buddy, right? - Yes - So just get out of here! Meaning this area is yours (you rather attributed the pitch to yourself and you do not want that guy to come and play on it - very offensive. I believe that example is stretching the meaning, though we sometimes use pitch that way in French
'Pitch' can also be used to mean the space where a temporary trader or busker operates - so 'You're on my pitch' could also used without reference to any kind of sport.
But 'on the pitch' isn't idiomatic (in any context I've met). Rather than 'on the pitch' people use another idiom - also related to sport - "in play"; and if a situation is developing, you can say '[we won't know] until all the balls are in play' (a bit of a strange idiom, now I think of it, as most games I can think of with several balls - notably snooker and pool - start with all their balls in play and the number of balls in play reduces). Hmm...
Eg We cannot tell [who is to win] until the time is running out meaning both players/teams can still try their luck to take the lead.