Alcohol exclusion laws are rules that say that your health insurance won't pay for certain types of medical treatment if you were hurt while you were drunk or under the influence of alcohol.
Think of it like this: when somebody is drinking alcohol, they might do things that they wouldn't normally do if they were sober. They might fall down and hurt themselves, or get into a car accident because they can't drive properly. If their health insurance paid for all the medical bills that came from those accidents, it might give people less reason to be careful when they drink.
So, the government made laws that say health insurance doesn't have to pay for those sorts of injuries if they happen while somebody is drunk. This is a way to encourage people to be more responsible when they drink, and to think ahead about the risks of getting hurt.
For example, if you got hurt while playing a sport, your health insurance would cover your medical bills. But if you were playing that same sport while drinking, and got hurt because of it, your health insurance might not cover the costs.
This is why it's always important to be safe and responsible when you drink.