The verb “be” expresses a state of existence.
It takes many forms and is the most inflected verb in English. In other words the verbs with the most number of different forms for different tenses, number and voice.
Essentially the verb be takes the following eight forms:
be, am, is, was, are, were, been, being
The infections of BE in three tenses and two numbers:
Apart from these, the “been” combines with helping verbs “has” and “had” and “will” to denote the perfect & progressive (continuous) aspect of the three tenses and also the future tense.
He has been in Germany for a long time.
He had been to England last year.
Next year, at the same time, I will have been doing my doctoral thesis in Languages of the Orient.
He will be fine tomorrow.
Being can be taken as the present progressive variant of “be” denoting an action in the present tense and that is continuous and progressing.
He is being nice to everyone.
Being also plays many other roles, such as a participle. That is a more advanced topic that we will deal with later.