Deploy action sends the Zenland contract and its data to the blockchain network specified by the parties in the contract terms. There, the information is processed by the nodes (individual computers) and added to the blockchain database.
Just like with any physical or digital database, the new contract is given the contract address. This address is the actual place in the blockchain where the contract, all its data, and funds (if any) reside.
More on the contract address, and its role in various contract operations, is here.
Once the new contract has been approved by both parties, it is deployed*, a.k.a. published to the blockchain.
Note that only the Contractee (buyer) deploys the Zenland contract. During the deployment stage, the Contractor does not take any actions and simply awaits the deployment.
Once deployed (published) to the blockchain, neither party would be able to change/edit the contract conditions. Make sure the contract terms are clear and have been thoroughly reviewed by both parties entering into the agreement.
Deployment of the contract changes the contract state, from draft to deployed. Like regular blockchain transactions, deployment transactions are time-stamped and can be traced through the Contract Chat.
Good to know
*As all blockchain transaction processed by nodes, the deployment request has a fee known as a gas fee.
More on gas fees and why they exist can be found in "What is Network".