Rooks are one of the most powerful pieces in chess. Rooks are worth 5 pawns or 5 points, depending on what you are reading.
The main thing you need to know about rooks is that they work best on open files, meaning that vertically and horizontally if there are no pieces in the way, the rooks fair much better. The rooks are only as good as the number of squares they can cover or the pieces that they can support.
One of the common mistakes people make is not activating their rooks. When you develop your pieces you should aim to move all your pieces towards the center, and after you have castled for king safety, make sure that your rooks are always on open files. If you lose one of your pawns, make sure you put a rook on that file. If chess players used their rooks more efficiently they would become much better players instantly.
Watch the video below to watch a detailed explanation of rooks.