Sure! This will come up in Lesson 3 as well- but briefly a Passive Alert is just that, sitting, lying down etc as a form of indicating she has found the desired odor.
An Active Alert such as scratching or digging, barking etc, is just that! active. There are reasons why scent work trainers and dogs (including truffles, narcotics, explosives dogs, etc) choose one alert over another, and that will be discussed in the next lesson. Basically Passive alerts are great, but for real world application when specifically truffle hunting they can leave some things to be desired. Don’t stress too much over it yet. Just keep doing what you are doing. We like to work with the dog’s natural tendencies as that makes learning easier, more fun, and more ingrained later down the line when things get exciting or stressful.
You will learn distinct passive alerts- most likely sitting, which I already see Lola doing as well, when you start your NW class.