Can you guys me understand what verb etre, verb avoir and what verb venir means and how do we use them?

Let's start simple: the verb être is, in infinitive form, "to be." It is conjugated in the present-tense as follows:

Je suis (I am)
Tu es (you are (singular, informal))
Il est (he is)
Elle est (she is)
Nous sommes (we are)
Vous êtes (you are (plural, formal))
Ils sont (masculine plural)
Elles sont (feminine plural)

If I wanted to say, "I am nice," I would say:

Je suis sympa.

Avoir means "to have":

J'ai
Tu as
Il a
Elle a
Nous avons
Vous avez
Ils ont
Elles ont

If I wanted to say, "He has an apple," I would say:

Il a une pomme.

Venir means "to come":

Je viens
Tu viens
Il vient
Elle vient
Nous venons
Vous venez
Ils viennent
Elles viennent

If I wanted to say, "You all are coming here," I would say:

Vous venez ici.

These three verbs are very basic and necessary for speaking and communicating in French.