We don't USUALLY use articples before the names of people.
However, sometimes we do when we add some description that mean "he or she was looking/acting a certain way."
It was a happy Anna who came home after finishing her final exams.
It was an Anna happier than we had ever seen who came home after finishing her final exams.
We also use the indefinite article before a name to mean "I don't know this person."
A Tom Smith called for you. He said he'd call back and didn't leave a message.
An Alice Montgomery called for you. She said...
We also use the definite article to mean that the person is well-known.
You met Brad Pitt waiting in line to play Skeeball at the beach? You met "the" Brad Pitt? (Not just any man whose name happened to be Brad Pitt.)
There was a funny episode on David Letterman where this middle-aged, normal man whose name happened to be Justin Beiber came as a guest. I have also seen an interview with a man named "Michael Jordan" who was not the basketball player that everyone knows. He said hotel clerks were always disappointed to find out he was not "the" Michael Jordan.
How did you plan to use it?
Student or Learner