Why phase raise_objection and drop_objection is required in test class run_phase?

In reply to dave_59:

could you please provide an example of this type of test class. Actually I am unable to understand the last line of your answer.
“Then you might have a scoreboard or checker waiting for some results, and has an objection raised waiting for the result to drop it.”-- means is this objection raise and drop will be inside the run_phase of scoreboard/checker?