We use the verb TO BE to express statements such as:
-Profession or occupation (e.g. My father is a doctor. I am a student.)
-Nationality or place of birth (e.g. I am Mexican. We are from Mexico City.)
-Name (e.g. My name is Diana. He is Robert.)
-Age (e.g. I’m 22. My daughter is 3 years old.)
-Marital status (e.g. We are married. She is divorced.)
-Interests and likes (e.g. My favourite color is black. Her favourite sports are tennis and soccer. We are interested in Science.)
The verb To Be without contractions is considered a more “formal” way to express in English. However, there are contracted expressions which are more common.
We can also use the Verb To Be when we want to talk about something specific:
There is Sarah.
Here is your coffee.
That is very nice from you.