Arson is the act of setting fire to something. Arsonists often try to set fire to buildings or other places that are important, such as a school.
A knucklehead is a person who is very stupid or foolish. They are often the target of jokes, and people often call them names that are associated with stupidity.
To trivialize something is to make it seem unimportant or insignificant. When the speaker says that the issue is trivial, they mean that it is not a very important issue.
To parade is to walk or march in a way that is intended to show off your strength or power. The soldiers were parading through the town to show off their military might.
To begets is to produce something that is related to or descended from something else. When you begets a plant, you're planting a seed and waiting for it to grow.
To mindfully something is to do it with your full attention. When you mindfully eat your dinner, you are paying attention to the taste and smell of the food, and you are not mindlessly eating it.