Let's break it down:
* Be: This is the base form of the verb "to be," which is an auxiliary verb.
* Able: This is an adjective that means "having the power, skill, or means to do something."
Together, "be able" act as a single unit to express the ability to do something. For example:
* "I am able to swim."
* "She will be able to finish the project on time."
While "able" itself is an adjective, "be able" functions as a verb phrase.