Pronouns take the place of a noun. "I", "he" and "we" are examples of personal pronouns. It's a good idea to use them to avoid repetition in your English writing.
Sometimes when you are writing and are caught up in the flow, just getting your words down, you might end up with a sentence such as this: "Sofia lifted her foot gingerly from the pavement. Sofia's shoe pulled a huge lump of chewing gum up from the pavement with the shoe, and Sofia watched as the gum stretched out to a remarkable length, tenaciously clinging both to the sole of Sofia's shoe and to the dirty pavement." Too much repetition of the name Sofia, and the word "shoe", becomes distracting here. Instead it would be better to replace "Sofia" with the pronouns "she" and "her" and "shoe" with "it" and "its". Then we would have the improved sentence: "Sofia lifted her foot gingerly from the pavement. Her shoe pulled a huge lump of chewing gum up from the pavement with it, and she watched as the gum stretched out to a remarkable length, tenaciously clinging both to her sole and to the dirty pavement." That's a bit better, isn't it?
Play this first quiz on pronouns and if you get full marks, see if you can match your score in our second quiz!