confirmed/unconfirmed for Bitcoin transactions refers to when a transaction is considered official. Usually (such as for the common BitCoin client app) this is when the transaction has been hashed into the original block and 5 subsequent blocks (e.g. it can be verified to have existed through 6 generations of successive blocks). Different apps can have different requirements, however.

I would assume that the mining pool uses some variation/extension on this system, referring to your hashing efforts, to reward credit to miners like yourself. I could be totally wrong though