The verb être in French is like the glue that holds words together into meaningful sentences. It translates as “to be,” “to be located,” or “to appear” and helps to say who you are, where you are, and what you are like.
In our language, we often just leave it out. For example, we say “I am a student” or “She is happy,” but it doesn't work that way in French. There you can't do without être: Je suis élève (I am a student) or Elle est heureuse (She is happy). If you forget this verb, the Frenchman simply won't understand you because the sentence will sound strange.
So if you want to speak French normally, you can't go without être. It occurs in a lot of phrases and tenses, so it's better to get used to it right away.