it says assess. It means you can work out your horse's max skills by inputting information. I did see the page once, but I can't remember what information it wanted. I'm sure someone will add that information who has added that perk to their VIP

It has different options to show for example:

How many skills will my horse have if I simply bold all skills.
How many skills will my horse have if I do lessons..Or give them a Water of Youth, different amounts of pieces of cloud.
How will the skill set look like if I take trot and put it into stamina with the beach rides.

Each of these options can be combined or only a few can be ticked to see exactly the end results of the horse.
It's a great way to plan the results if you want to enter a specific competition threshold or train a skiller for Grand Prix, calculate the end skills for a newborn foal and so on, without the hassle to calculate it manually on your own.