The full moons have descriptive names that come from Native Americans and Colonial Americans who used the full moons as a sort of calendar to keep track of the seasons.
July is the month of the Full Buck Moon. According to the Farmer's Almanac, the Full Buck Moon comes from the fact that July is"normally the month when the new antlers of buck deer push out of their foreheads in coatings of velvety fur." It's an observation borne out in science. Deer regrow their horns every year, and July is when deer testosterone levels begin to rise. This Full Moon was also known as the Thunder Moon because thunderstorms are so frequent during this month. (source)