Masternode is a node (computer, server) running on the network with a cryptocurrency wallet running on it with a certain number of coins.
Masternodes are responsible for locking and confirmation of the transaction (4-5 seconds) - InstantSend; the mixing transaction (i.e. data encryption) - PrivateSend.
Kzcash Masternode requires:
at least 1,000 KZC on balance;
availability of a dedicated IP-address;
availability of uninterrupted operation of the system 24 / 7 (provided communication loss - no more than 1 hour).