Tara goes to school every day. She meets a new girl in her class. The girl’s name is Sasha.

The word girl is a general name. It is a common noun.

The words Tara and Sasha are the names of specific people. They are proper nouns.
A common noun is a general name for a person, place, animal or thing.
A proper noun is the specific name of a person, place, animal or thing.

Remember: Every proper noun begins with a capital letter.