What is 'the kings' in Latin?

"Rex" is a Latin equivalent of "king."

The Latin Word is a masculine noun. Latin has no definite articles ("the"). But the singular indefinite article would be "unus" ("a, one").

The pronunciation is "wrecks"* in the liturgical Latin of the Church and the classical Latin of the ancient Romans.

*The sound is similar to the English verb "wrecks."