Please take this medicine after a meal.
I had fruit for dessert after the meal.
Please take this medicine after meals.
Take the medicine within 30 minutes after eating.
Lying down right after eating isn't good for your body.
I'm looking forward to the coffee after the meal.
食後 refers to the time right after eating, whereas 食間 refers to the interval between meals (e.g. mid-morning or mid-afternoon), a distinction that matters especially in medicine dosing instructions.
Compound of 食 (shoku, 'meal, eating') and 後 (go, 'after').