A chef — a professional cook, often referring specifically to a head chef or professional in a kitchen.
あのレストランのシェフはフランス料理の経験が長い。
The chef at that restaurant has extensive experience in French cuisine.
シェフに新しいメニューの意見を聞いた。
I asked the chef for his opinion on a new menu.
若いシェフが開いた店が評判を呼んでいる。
The restaurant opened by a young chef is getting good reviews.