Verb:
* Present tense: She calls her mother every week.
* Past tense: He called her last night.
* Future tense: I will call you later.
Noun:
* Plural of call: The phone rang, but there were no calls on the display.
* Referring to a specific type of call: We received several calls about the outage.
To determine whether "calls" is a verb or a noun, consider its role in the sentence. If it's the action being performed, it's a verb. If it's the subject or object of the sentence, it's a noun.