Here, I want to share just a basis for learning everything you need to know about personal pronouns. Just like nouns, they can have different functions in sentences, so we will need to use different cases of them. But, when we first learn nouns, we learn their nominative form and then later, we see which form we need and how we will get it. That's why in this topic, we will only learn how the personal pronouns look like in nominative, and later we will see them in other cases.

Singular:

1. ich - I
2. du - you
3. er/sie/es - he/she/it

Plural:

1. wir - we
2. ihr - you
3. sie / Sie - they / you (formal)

In German we also have a pronoun Sie with capital S that is used for "you" when we want to show respect for somebody. Let's see it on the example:

We want to let the person standing next to us that they are next in the row ("you are next"). For purpose of this example, I will not write sentence with first capital letter as it is supposed just so it is clear what is the difference.

du bist der Nächste ----- if we are telling this to some kid for example

Sie sind der Nächste ----- if we are telling this to some older lady

We can notice too that Sie uses the same verb form as sie (they), which is logical from its position in the list of pronouns.