Can someone explain to me what is the "Zerocoin" menu in the client for? Can we mint zerocoin, is it another coin?
It's a financial privacy feature. Core feature of the zerocoin protocol zoin is based on. Someone described it here:
It will mint a new single coin that comes from nowhere. It's a 0. Transaction coin
It has a transaction fee of .001 and you have to have one to mint it...
It is how you make untraceable transactions
The idea is you can mint a zerocoin which costs some amount of the normal currency (here zoin). The later you spend that zerocoin and receive some normal currency back, to a brand new different address that has never been used before. The mint operation and the spend operation are supposed to be unlinkable. Meaning you end up with new currency that has no history. It's completely anonymous and not connected to any of your previous transactions. Normally all your spends are connected to previous receives and anyone can follow the whole chain.
If it works as advertised you can use it to keep your block chain transactions anonymous.