"A good move" is something you do that is smart and has a good result for you:

Buying a house would be a good move for us financially.

This phrase might be related to the game of chess. In chess, each player's turn is called a "move". If you do something that's smart and helps you win, someone might call it "a good move". So if you imagine life as being similar to a big chess game, you can understand why people use the phrase "a good move" to talk about smart decisions or actions.