Direct address is when you use a person’s name or another word to indicate that person (lady, man, dude, jerk, Mom, Dad, pal, dear, darling, etc.). That direct address should be set off with commas:
Sweetheart, I miss you so much.
I’m telling you, Dad, you need to stop working so hard.
Cut it out, idiot!
Yes, Virgina, there is a Santa Claus.