Is WARNS a Wordle Word?

Yes. WARNS is a valid Wordle word.

It is not on the Wordle answer list, so it is unlikely to be a daily answer.

Plurals ending in S are almost never chosen as Wordle answers.

What does WARNS mean?

To make (someone) aware of (something impending); especially:
To caution or admonish (someone) against unwise or unacceptable behaviour.“Don't let me catch you running in the corridor again, I warn you.”
(chiefly with "off", "away", and similar words) To advise or order to go or stay away.“A sign warns trespassers off/away from the site.”

1 more verb definition

Definition from Wiktionary, available under the CC BY-SA license.

Starter word rating: AverageIn the top 26% of all valid Wordle words for testing common letters.
Vowels: A
Unique letters: 5 of 5
Common letters: A, R

Hard-mode trap: 10 valid words fit the pattern _ARNS. If you reach it, you may need several guesses to find the last letter.

Letter ratings use how often each letter appears in Wordle answers.

Tap its tiles to the colours Wordle showed, and the Wordle Solver lists every word that still fits, with the best next guess.