At a regular table, you have 14 seconds to make each decision before being 'timed out'. There's a time limit, so the players stay engaged and active in the room, and so no-one is kept waiting too long! If you do not make any action within the allotted 14-second window, when facing a bet or raise, your hand will be folded, and your state changed to 'sitting out'. If you are not facing a bet or raise, i.e. no player has bet or raised on the current betting round, or you are first to act, you will check. Don't worry, you can return to the game at any time after sitting out, providing you still have chips.