Break Even means that a player is even and made no plus and also no minus. That can be in a single session or also long term. There exist for example many break even players who make no winnings from the game. Just because of the rakeback the get their winnings. Break Even players are no fishes but also no poker sharks.
A lot of players make the mistake to fight so much for a break even session when they have a bad run. They want to force it, to reach the break even and do not want to stop. Most of the time this does not work and they go even broke because of tilt.