The csv file contains the press history for /r/thebutton.
The csv has four columns:
press time the date and time at which the press happened
flair the timer value the user got as flair
css the flair class given to the user
outage press whether the press was an automatic press during a site outage to keep the button alive
Outage presses were relatively few and never occurred at a time when the button was truly at risk of expiring, but if you're doing real scientific analysis on this data, you may choose to discount these presses or otherwise make a note of them.
Source code for the button is at https://github.com/reddit/reddit-plugin-thebutton.