NEVER, EVER, DO THIS.
The young person who picked this harbor seal up said that this pup was in danger of being run over. Maybe it was, maybe it wasn't. But now that pup is definitely in high danger of dying.
Why? Harbor seal mothers can temporarily leave their pups on the rocks or on a beach. Or the pup might have lost its way while its mother fed during high-tide. There could be many reasons why it is on the beach.
But it is illegal to handle a marine mammal, and it is dangerous. Call a grown up and have them call a marine mammal rescue center right away.
Harbor seals give birth to their pups in the spring.
Here is what the experts at the National Marine Mammal Laboratory have to say about harbor seal pups: "Harbor seals inhabit areas that are also frequented by humans and are easily disturbed. When disturbed the mothers sometimes abandon their pups. Do not try to approach them, the mothers will be back soon to take care of them."