How are perks from wises spent?

Upon completing the 4 wises tests it says you get a perk. This is a Beginner’s Luck or advancement test apparently. Does that mean the player rolls again? If so what obstacle are they rolling against? How does this extra roll play out narratively?

Or does it mean they automatically mark off a pass or fail towards learning a skill? Can they choose a pass or fail? Or do they immediately acquire a rating in the skill?

I’ve read the section on wises and abilities a few times but I’m still uncertain how this works. I’m not sure if the text is telling me it counts towards advancement automatically or if another test is required. When the text says test, I assume it means a roll. It seems to be saying to make another roll, but it makes no mention of the details of the roll.

I’ve thoroughly confused myself here, and would be very grateful for any untangling people can offer.

Mark off a pass or fail, your choice.