Open, closed, and semi-open games
There are three main categories of positions. If there are few pawns on the board the position is open. Bishops are often very strong in these positions because they are not blocked. If there are many pawns blocking each other on the board, the position is considered closed. Bishops are restricted by the pawns in these positions, so knights are the dominant minor piece. Many positions have some features of open and closed positions, and are considered semi-open.
Black wants to open up lines to bring the rooks into action - which pawn move helps with this plan?
Great job, you opened up Black's rook on the c-file. Let's make another trade to force open the c-file.
White should have recaptured with the c-pawn with an equal game, but White tries to keep the c-file closed. Let's force it open with another trade.
Black has forced open the c-file. How should Black best put it to use
Black attacks the weak a2 pawn and will dominate the c-file on the next move with ...Rfc8.