Hello Tony,
You are right, the shortest formulation for lease in this context is the one you wrote: get a task and then run it. There are still some other important elements to this: leasing a task makes it unavailable for processing by another worker, and it remains unavailable until the lease expires. This is an important aspect: no other worker has access to the task that was leased, not until this lease expires. It follows, as expected, that once a worker completes a task, it needs to delete the task from the queue.