Suspended is a game term used to describe when a player's account has put in an un-playable state.
When used in an account billing perspective, it just means payment has not been received when the collection was attempted so service has been revoked. The suspension lasts until payment is received.
When used in an administrative perspective, it's usually as a disciplinary measure imposed by the game company upon the player for breaking one of the Rules of Conduct, commonly Harassment of some sort, but also for doing things illegally such as exploiting or otherwise cheating. Suspensions of this nature are usually measured in days(usually 24 hours) and differ from bans in that bans are almost always permanent.