If you are not reading this article in English, I highly recommend that you turn off the automatic translation on your browser.
The prefix “pro-” derives from Latin and signifies “in place of”. That means that pro-nouns are words which substitute nouns.
If pronouns didn’t exist, we would be forced to repeat nouns over and over again, resulting in a rather annoying communication.
There are different types of pronouns:
Whose (Object possessed by an unknown subject)
This is a complete list of English pronouns, you don’t need to memorize them all out of context, they will become familiar to you through practice. Take that list as a reference. You can consult it whenever you want.