Poker sites give each player a time bank. The length of this depends on the game format. If you have disconnected, then you will get extra time added on during a tournament. After that, your hand will be checked, or if someone has raised and the disconnect means you do not call, your hand will be folded. This happens even if you put money into the pot. For tournaments, you will then continue to pay the blinds and antes until you have reconnected.
In cash games, you will typically lose your seat if you are sat out of a game for two orbits.
This highlights the importance of a stable connection, especially if you are playing for higher stakes.