Here is an example i see in cource code off bunny finance https://github.com/PancakeBunny-finance/Bunny/blob/main/contracts/vaults/venus/VaultVenusBridgeOwner.sol#L52
There are two ways to create references to contracts:
Deploy a new instance with
Contr c = new Contr(possible_constructor_arguments);
Reference a contract which has already been deployed:
Contr c = Contr(address_of_contract);. Here
Contrcan either be an interface or the contract implementation (if you have its source code).
So, to answer your question, the line is referencing an existing implementation of the contract at address 0xABCD. It uses an interface so that the interface's functionality is available for the reference (so you can actually call the contract's functionality).