I haven't used FaucetBOX but I've used Microwallet.org and Bitchest.me and if they are any similar, then what happens is you submit your normal Bitcoin address to the faucet. The faucet then sends satoshis (typically a few hundred satoshis) to Faucetbox. The reason why it can't send these satoshis directly to you is because the Bitcoin network enforces a minimum transaction size of 5,430 satoshis. Instead, by entering your normal address on Faucetbox, you can see how many coins were sent to your account from the various faucets that you used. After Faucetbox collects enough satoshis from these faucets for a proper transaction to happen (typically 5,430 satoshis but this might be changed to a higher limit), it will finally send these satoshis to your actual Bitcoin wallet.