Sentences can be written in the first, second or third person.
When we are talking about ourselves we use the words I and we. This is called the first person.
If we are talking to somebody else we use the word you. This is called the second person.
You must go to bed now.
If we are talking about other people we use their names or the words he, she, it and they. This is called the third person.
Jayden is coming to my house tonight.
They are getting a new puppy.
She is older than me.