It displays an interactive map of his association's marina, showing all the berths and the boats in each berth. Clicking on a boat displays details of the boat and (if the user is logged in as a member) it displays contact details of the boat owner. It also allows you move boats from one berth to another, or from the waiting lists at the bottom to an empty berth. All changes update the database. Having made a change the map is redrawn.
As you can see from the image below, it worked when it left the shop (login too, so it can display the owner details). I wrote this, and a few other pages, for Leon as a hobby project during the lockdown.
If you examine the lower right-hand edge of the image you will see my name. When he put it on his site that name had been removed and he added footer proclaiming "Design and Development by...<his site>". If you look at the posted code (line 300 - about halfway down - my name is there but now commented out). I told him that as he wanted to claim all the credit for the design and developent then he should actually do it all. I then ceased communication.
Given that history, it seems strange he should be publically crediting me now he has screwed with the code and it has all gone FUBAR. Whether he intends it as blame or just to try and embarrass me into helping out, I'm not sure. But it does give me no choice but to explain publically why I am not rushing forward to help with his problems.