There are two kinds of time in chess. The first and obvious is the ticking chess clock. Each player gets a limited amount of time for the entire game. The golden standard is 90 minutes for 40 moves followed by 30 minutes for the remaining moves including a 30 second increment per move starting from the first move. The second and perhaps less obvious is the tempi or the moves themselves. It is the number of moves that it takes to perform a planned action. For example, if you plan to bring your king to the center using Kg1-f1-e2-e3-e4, this takes 4 moves so the tempo time is equal to four. Pretty often you hear the phrase "that is a great plan but it is too slow". In this context, slow refers to the tempo time, it just takes too many moves to perform the planned action.
Taking tempo time into account is important, because for every extra move that you need to perform an action, the opponent gets one extra move for reaction. For example, if you plan to do Qd1-g4 and then put a bishop on h6, then it would be strange to start this with Bc1-e3. A plan is generally directed to reach a certain goal, for example to increase the pressure on a weak pawn. This goal can be reached using different pieces going to different squares in a different order. In such a situation, tempo time goes both ways. If you force the opponent to react in a passive way, for example when you threaten a weak pawn with a piece then the opponent uses a piece to protect it, then you are using your tempo time better than the opponent and thus increasing your advantage. Therefore, the best way to perform an action is to choose such moves and order of moves so that the opponent's tempo time is used in a less improving way than yours.
Understanding the different pieces and how they cooperate is important to calculate tempo time in a good way. Different positions have different levels of sensitivity to tempo time. Tempo sensitivity depends on how well the kings are protected, on the pawn structure, on the number of open files, on the pieces that are still on the board, on the number of passed pawns, etc. Figuring out the level of tempo sensitivity of the position on the board is an important part of figuring out the key components of the position. Try to plan in a tempo efficient way.