Determining parts of speech is nothing more than determining the function/job a particular word has in a sentence. They all play a role in the sentence, and one word might be a noun one time and a verb the next.
Let’s take the word run for example.
Let’s go on a RUN after school. (NOUN)
I will RUN to the cafeteria to be first in line (VERB)
NOUNS person, place, thing, idea
Common : chair, pencil, school
Proper : Woodward Academy
Concrete : desk, Aunt Lulu
Abstract : freedom, love
Compound : firefighter
Collective : class, herd
Pronouns, for the most part, take the place of nouns.
There are actually several different kinds of pronouns, and they are used much more than most people realize.
PERSONAL PRONOUNS - the basics
FIRST PERSON : I, me, my, mine, we, our, ours, us
SECOND PERSON : you, your, yours
THIRD PERSON : he, she, it, its, his, him, her, hers, they, their, theirs, them
THIS, THAT, THESE, and THOSE
ONLY used in place of nouns ( be aware of Demonstrative Adjectives - don’t use them before a noun ).
THIS is my book.
THAT is yours.
THESE are my pickles.
THOSE are his shoes.
WHAT, WHICH, WHO, WHOM, AND WHOSE
And like all interrogatives, they start questions:
WHAT are you doing?
WHO do you think you are?
WHO, WHOM, WHOSE, WHICH, THAT
These look like interrogative pronouns, but they do NOT ask questions.
They begin clauses that add more info to a sentence:
My students, WHO are the best and brightest, love relative pronouns.
The vegetables THAT are the healthiest are the green ones.
An indefinite pronoun refers to something that is not definite or specific or exact.
The indefinite pronouns include but are not limited to the following: