"To Be" in German, each verb (action word) changes depending on who the verbs refers to ( I, you, she, we and so on) as well as the tense (such as present, past, or future). These changes are called conjugations .
Resources for further reading:
Have a look at the conjugations of the verb “sein” to be in the present tense.
Check out this free lesson on "to be" in German!

How to pronounce "to be" in German
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Singular
Plural
“Sein” is a very important verb that you will be using all the time.