This site is run by Eitan Suez.
Signing in with Google writes an activity log. The line has your email, your name when Google supplies it, and the time. Starting a lab adds the lab and the time you started. Completing the lab records that time as well. On an event set, the form supplies your name and email, and submitting it writes that line.
Some labs have a completion badge. Completing one of those labs sends the same name and email to Credly, which issues the badge. If the first name, last name, or email is missing, the badge is not requested. A lab that stops on its own does not request one.
The activity log is for the site admin. It is not shown on the lab list. Your profile shows the labs you have taken and the badges you have earned.
A Google sign-in is also remembered for a short time, so the admin page can show who is here. That list is separate from the activity log.