What part of speech is the word falls?

The word "falls" can be two different parts of speech, depending on its context:

* Verb: It's the third-person singular present tense of the verb "to fall". For example: "The rain falls heavily."

* Noun: It's a plural noun that refers to a cascade of water, like a waterfall. For example: "Niagara Falls is a famous tourist destination."

To determine the correct part of speech, you need to look at the sentence and how the word is being used.