Re: what are they
A playground is where children play on slides, swings, climbing structures, etc.
It is not used for the fields (pitches?) that have lines drawn on them for organized team sports. In the US, we refer to those just as "fields." The football field, the soccer field, etc.
However, I'd be interested in seeing which sports have a "pitch" since that word isn't really used here.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.