Yes, “is” is a verb. It is a form of the verb “be” that is used with third-person singular subjects (e.g., “She is my best friend”).
“Is” can be used in two ways:
As a linking verb, which is used to describe the subject’s condition, state of being, or identity (e.g., “He is a nurse;” “It is bedtime”)
As an auxiliary verb (aka helping verb) to change the tense, mood, or voice of a main verb (e.g., “She is singing tonight”)
QuillBot’s Grammar Checker can help you make sure you’re using “is” correctly.