A pronoun is traditionally a part of speech in grammar, but many modern linguists call it a type of noun. In English, pronouns are words such as me, she, his, them, herself, each other, it, what.
Pronouns are often used to take the place of a noun, to avoid repeating the noun. For example, instead of saying
- Tom has a new dog. Tom has named the dog Max, and Tom lets the dog sleep by Tom's bed.
it is easier to say
- Tom has a new dog. He has named him Max and he lets him sleep by his bed.