Verbs and Adverbs

Verbs are "doing" or "action" words.

For example the words to speak is a verb
"to run" is another verb
A verb is mainly used with a "subject" such as I, you, he, she, we, you, they..These are called "PRONOUNS"
When we use those words as a subject, we also use a very important verb called "to be"
e also use NOUNS

The verb "to be" is then "conjugated" which means to give the different forms of a verb as they vary according to voice, mood, tense, number, and person.
I am
You are
He is
She is
We are
You are
They are

are all examples of conjugation.
We then use "adverbs" to add to the meaning of the verb
I am speaking
You are speaking
He is speaking ....and so on.....the word "speaking" is an adverb

Using the verb "to be" is the main area where people who are learning English make the mistake of not using the verb.
For example, if a person is talking to his mother,  they might say "I talk to my mother" instead of "I am talking to my mother"
If he is cooking the dinner, he might say "I cook the dinner" instead of "I am cooking the dinner"
or "I walk to the shop" instead of "I am walking to the shop"

You can see that in these examples, using the correct English sounds much better.
You can also look at the "Tenses" category to see how the verb "to be" is used for present, past and future English.