Semi-vegetarianism is when people mostly eat plants like fruits and vegetables, but they sometimes also eat meat. It's kind of like being a little bit vegetarian, but not fully.
Imagine you really like ice cream, but sometimes you also like pizza. But you know that too much ice cream and pizza isn't good for your body. So, sometimes you eat salad and fruits with your meals. That's kind of like being semi-vegetarian. You eat mostly plant-based foods, but you also eat some meat, just not all the time.
Semi-vegetarianism is a good way to make sure you are getting enough nutrients from plants while still enjoying some meat in moderation. It's also good for the environment because eating a lot of meat can have a big impact on the planet.