Great question. These are two different uses of de.
In plateau de jeu:
So:
French often uses de + noun to create this kind of descriptive phrase.
A simple approximation is:
A few pronunciation notes:
So the whole sentence is roughly:
That is only an approximation, but it can help at first.
Yes. Pioche can have different meanings depending on context.
Common meanings include:
In a board-game sentence like this one, la pioche usually means the pile of cards or tiles players draw from.
So context is very important with this word.