Attendance has to do with being present at something, like work or school. If you never miss a day, you have perfect attendance.
The concept of attendance has to do with showing up: if you show up for school, then your attendance is not in question. When people miss school or work, they usually need a note from a doctor, explaining why they weren't in attendance. We can also say "The attendance was 100" if 100 people showed up to a meeting. If only three people out of 100 showed up though, you'd say, "Wow. Attendance was terrible."