English penal laws are like rules that the government makes to keep people from doing bad things. It's like when your parents tell you not to hit your sister or brother or else you'll get in trouble.
Back in the old days, English leaders made a lot of rules about what people could and couldn't do, like not going to church or not following the rules of the government. If people broke those rules, they could get punished by being locked up in jail or by being fined (which means they had to give the government money).
Some of the strictest English penal laws happened in Ireland when the English government rulers were trying to control the Irish people. They passed a lot of laws that made it illegal to be Catholic or to speak Irish. Those laws were really unfair and caused a lot of problems for the Irish people.
Thankfully, as time went on, people started to see that these strict rules weren't fair and they were changed. Nowadays, there are still rules in place to keep people safe, but they are much more fair and reasonable.