が入ってるよ

there's ... in it

→ が
phrase Rare #26,288
there's ... in it Used to point out that something is inside or contained in something. 入ってる is the casual form of 入っている, and よ adds emphasis or informs the listener.
JA: このスープには魚が入ってるよ。
EN: There’s fish in this soup.

このお皿ひびが入ってるよ

This plate is cracked.

全員棺桶片足が入ってるよ

Everyone has one foot in the grave.

— 8 1/2 (1963)

冷蔵庫にヨーグルトが入ってるよ

There’s some yogurt in the fridge.

冷蔵庫に牛乳が入ってるよ

There’s milk in the refrigerator.