。
It's time for dinner.
Literal
Dinner-of time is-[polite-ですよ].
A simple announcement with the friendly よ at the end — typical of a parent calling the family to the table. The structure [noun]-の時間だ/です is the standard 'it's time for X' template: 食事の時間, 寝る時間, 学校の時間. Direct and cheerful.