Your estimated reward is the estimated number of bitcoins you will receive when the pool finds a block.
Rewards cannot be sent to your wallet until they have been confirmed. Explanations on confirmed and unconfirmed rewards can be found here:
https://mining.bitcoin.cz/faq/ (under payouts).
how long would it take until I actually mined that ammount
You never actually mine any coins*, you simply contribute shares to a pool and then when the pool finds a block it pays you based on the number of shares you submitted.
*Unless you get really lucky and find a block. The only difference in this case is you mined the coins from which the pool pays everyone, but you still get payed the same amount.