What dose mature status​​​ mean ?

A mature block is one that has been confirmed by a sufficient number of subsequent blocks. For XMR I think that is 60 confirmations, so I think about 2 hours.

So dose that mean that payouts are every 2 hours ?

Payments are processed every ten minutes, but like happy has outlined, the payment processor has two wait until it sees enough confirmations for a found block on the blockchain to unlock the block for payout of the blockreward. This is done to protect the pool from paying for blocks that might become orphaned later on due to a chain split. 

Monero requires 60 confirmations (2 hours approx), Ethereum based currencies require only 15 confirmations (~5 minutes) and everything else requires 100 confirmations (roughly 4 hours).

I have been mining on here for around 12 hrs but earned nothing.. how can this be, sorry if i'm being stupid, i never mined before   

Have seen any block in the unlock stage for the past twelve hours? 

No i haven't

Our XMR pool is very small and thus requires days to find a block. If your goal is more frequent but smaller payouts, you're better of joining one of the Megapools such as supportxmr or nanopool.

ok i i think i understand how things work, so i have to wait until a new block is found and then payout are given ?

Yes exactly. There are also pools that pay for every share but due to the high risk for the pool, they take much higher fees (> 7%).

Depending on your mining hardware (hashrate) you will probably have to wait for longer than that.

You will be credited after a block has been mined (and confirmed) but you won't be paid until you reach the payment threshold so unless you got some powerful hardware it will probably take more than one block to receive payment.