Definition of move
When we talk about "making a move", we mean making a game that is not classic. Doing a "move" is literally making a move, but in the expression, there is a sense of urgency. Several examples could be given. In tournament play, one could say "I only have 5 big blinds left and the blinds are going up soon, I'll have to make a move soon". In other words, the player will have to make a all in soon, even if he doesn't have an excellent hand. In games of cash games you might hear: "This player has me 3bet five times in 30 minutes, I'm going to have to make a move". In other words, he's probably bluffing me, I'll have to bluff him again.
Choosing the right time to do a move
The move is not always imperative, but there is often a sense of urgency and fit in the word. A move is playing a game that is out of the ordinary. If we push all in preflop with 99 because a player keeps pushing us 4 bet all the time, we have made a move. Normally, it is not in our habits to push all in 100 big blind of the 9, but against a hyper aggressive player, there is an urgency to act and make a move. Keep your eyes open to identify the perfect moment to make a move.