know where to stand.... and when to move.
The pickleball court is about 1/4 the size of a tennis court. This is a bird's eye view of the layout:
Both the serve and the first return must bounce one time on the other side of the net before being hit. Therefore it is important for those players to stay near the baseline until the second volley is hit. Then it is usually advantageous for players to move up to the no volley line. However, one of the early learning challenges is that a player is not allowed to stand in the 'no volley zone' or, 'the kitchen' as it is called in my group, unless the ball bounces within that area before a player steps in and hits it. Notice how the players in the picture below are at the no volley line, with the exception of Mr. Red.
Another facet of knowing where to move is to remember that the server on the serving team moves from the right side of the court to the left side, and back, until the service is lost. So, the server's partner must move from one side of the court to the other. However, the receiving players do not switch sides.