A multisignature escrow is a special Bitcoin Cash address in which several people must sign a transaction in order to move the funds. In Bitgree 2-3 multisignature is used, so 2 signatures of 3 people are required. The people who can sign are wish's user, proposal's user and Bitgree.
Under normal conditions, wish's user signature plus proposal's user signature are sufficient to move the escrow funds. But in the event of a dispute between them Bitgree comes into play, which will be decisive in moving the escrow funds, thus unlocking the situation.
Normally the escrow funds are only moved at the end of the agreement, passing the funds to the proposal's user wallet. However, it's also possible to request a custom transaction in cases of emergency, although you will need the other party to accept it. Funds can also be exceptionally moved through a dispute, in which the signature of the dispute winner and Bitgree will be used to move the funds.