Don't be alarmed.
Seeing the word "busy", might scare some people. However this "busy season" is just a term to refer to when most clients are seeking out a photographer. This is in the early summer months, and up until late Fall/Winter time. The traditional sessions that people are looking for are: family, newborn milestones, highschool & college graduates, professional headshots, and weddings.
Obviously when it's the warmest time out of the year, especially here in Michigan, most people will want to get pictures done during this time of year. The warmth of the summer air, and the sights of the beautiful fall leaves are very appealing in images.