Hi, Dana! I’m going to try to do some justice to Kuh’s work when it comes to answering your question, but know that there’s an entire book on it, so any succinct summary is reductive.
Basically, Kuh found these practices by observing significant positive differences in outcomes measured by the National Survey for Student Engagement. Across demographic variables, students who participated in these practices reported higher levels of positive outcomes. Not surprisingly by the nature of the survey, student engagement and retention were significantly higher as well as reported levels of advanced approaches to learning. The ten practices are listed and describe well here in an excerpt from Kuh’s work:
https://ueeval.ucr.edu/teaching_practices_inventory/Kuh_2008.pdf
Speaking from the perspective of a student affairs educator, a lot of what I end up seeing is the more qualitative effects of these 10 practices. When students engage with the practices, the transformative nature of the practices becomes apparent. It’s amazing some of the insights that students bring to the table when these practices are done well and they take the time to engage and reflect. Based on what I have seen and experienced, I’d say that these practices are where classroom learning and beyond the classroom learning intersect and students are able to make the connections of how classwork applies to the “real world.”