What is this address and for what? 0x000000000000000000000000000000000000bEEF
This is likely a public address with no known private key, which can be used by convention for a set of actions available only to the contract owner (since no one has the private key of this address).
For example, the owner of an ERC20 token contract can implement a pair of
onlyOwner functions for minting tokens at this address, and for transferring them from this address to some other address (an address whose owner DOES have the private key of).