Thanks for asking this question.
I too learned this concept after seeing this question.
Primarily, SEO Siloing is a method to structure your page categories. You need to follow certain themes rather than doing your SEO randomly for a set of keywords.
You need to follow a clear central theme with Siloing a website with subject relevance and will lay the groundwork for high keyword rankings.
I hope this reference might help you understand the subject in-depth. https://www.bruceclay.com/in/seo/silo/
All the best!