。
Dinner's ready!
Literal
Dinner [subject-が] become-done-[past-た]-[sentence-final-よ].
Plain casual call to the table. The plain form できた (rather than the polite できました) plus the friendly よ gives this the feel of a family member announcing the meal — relaxed, warm, immediate. The polite-formal counterpart 夕食の用意が出来ました would fit a host announcing dinner to guests.