Is FESTS a Wordle Word?

Yes. FESTS 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 FESTS mean?

(in combination) A gathering for a specified reason or occasion.“a Renaissance fest”
(in combination) An event in which the act denoted by the previous noun occurs.

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

Starter word rating: WeakIn the top 64% of all valid Wordle words for testing common letters.
Vowels: E
Unique letters: 4 of 5Repeats S
Common letters: E, T

Hard-mode trap: 15 valid words fit the pattern _ESTS. 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.