What do you mean by this lines all men and women are merely players they have their exits and their their entrances?

The players here means like those players in theatres, and they are comparing the people to the players. So when they have their entrances, they means that they are born in the earth and when they have their exists, they are dying and leaving the earth. Which also means that the players would comeback to the earth, just like when they comeback to the stage.