Correct spelling, explanation: the word plays is either a verb in the third person singular of the Present Simple tense or a plural form of the noun play. In the case of a word that ends in two vowels, we don’t need to introduce any changes to the word when we want to add the -s ending. Therefore, the only correct form of the word is plays.

Definition of plays:
1. verb (3rd person Present Simple singular) – to have fun, spend time doing something entertaining, or take part in a sport or game,
She plays football at the local pitch twice a week.
2. noun (plural form) – a sport or a game,
He presented a few wonderful plays in the last tournament.
3. noun (plural form) – a piece of writing acted in a theatre,
He is the author of several brilliant plays that were shown in theatres around the whole world.

Expressions with plays:
The verb to play is a part of many common expressions:
1. play it by ear – to act spontaneously,
She is not a good decision maker and often just plays it by ear.
2. play it safe – not take a risk,
He is not a risk-taker and always plays it safe.
3. play your cards right – to act in a way that puts you in a position that lets you succeed,
He is a clever businessman who always plays his cards right.

Incorrect spelling, explanation: it frequently happens in English that when we want to add an -s to the word which ends in -y, we change it to -i, and then we add an -es ending. However, it happens only when a letter before -y is a consonant, e.g cherry – cherries. When a letter before -y is a vowel, we simply add -s, without making any changes. Thus, playes is an incorrect form while plays is a good one.