The executed state of the contract indicates that it is been finalized, and no action has to be taken by the parties. At this point, the Zenland contract, a smart program run on the blockchain, has read and run all its instructions (functions) written in code, a.i. has executed the code.
Like the real-life formal contracts, all Zenland contracts are stored on the shelves (blocks) of the database (blockchain). The only difference is that no contract is ever discarded and can be found for as long as the blockchain exists.
Executed contracts cannot be disputed, altered, or influenced in any way. These are the blockchain rules that all smart contracts follow.
For more information on the blockchain and smart contracts refer to the "Getting Started" section.