Meat-free days mean you get to eat things which are not meat. Do you remember eating vegetables, fruits, whole grains, and beans? These foods are super tasty and amazing for your body as they make you strong and healthy. So, when you have meat-free days, you eat these kinds of foods, and animals like cows, chicken, pigs, etc. do not have to be killed for you to eat. It is like giving the animals a break, and it's great for the environment too! So, on meat-free days, you just eat all other kinds of food except for the meat bits.