What is Yan Site? How is it made?

[Barry]

I watched a video where it was said that creating a side website without dragging down the main site could be beneficial. I want to create a side website just for sharing poems on my blog. I will do this using the Blogger platform, and the design of the sites will be the same. I will also link them to each other. However, I'm not sure if using the same name that appears on Blogger for the side site would have any negative impact on the main site. Can someone who knows what a side site is and how it is created explain this to me?