We use personal pronouns to replace names we've already mentioned, talk about ourselves, and talk to and about other people and things. In English they are words like "he," "you," and "them."
Personal pronouns show the gender, the number, and the case of the noun they represent.
(used with friends, family, and in informal situations)
(used with bosses, strangers, and in formal situations)
Personal Pronouns have the be declined - changed based on which case they are in.
In first person, we are talking about ourselves.
In second person, we are talking about the person / people we are talking to. Note that "Sie" and its other forms are written with a capital letter.
In third person, we are talking about other people or things (neither the speaker nor the listener). We use them instead of the normal nouns or names because it's obvious who we're talking about, or we've already mentioned their name before - and using the personal pronouns is shorter.
If you're not sure it's obvious (i.e. two nouns with the same gender are involved), it's better to use the actual nouns to avoid misunderstandings.
(Who? Die Katze or Frau Meier?)
We use personal pronouns to replace names we've already mentioned, talk about ourselves, and talk about the people we're speaking to.
There are different pronouns depending on who we're talking about it (their gender and number) and their function in the sentence (their case).