"Having the move" — in French, le trait — means it is your turn to move a piece on the board. In chess, both players strictly alternate moves, and knowing whose turn it is is fundamental to reading any position correctly.
Having the move can be a significant advantage. The active player can launch an attack, create a threat, or force a precise response from the opponent. In contrast, in certain positions known as zugzwang, having the move becomes a disadvantage, because every available move worsens one’s own situation.
In practice, always identify who has the move before evaluating a position. A position that looks equal can tip decisively depending on whose turn it is. In a tense pawn endgame, for instance, having the move can be the single factor that determines the result: with the move, the king advances and wins; without it, a critical tempo is lost.