If you designed your own single listing page, you might be using related listings. You can use the Related Listing widget, but for most people, there is a better choice. You can use the Listing Grid widget.
The MyListing Toolkit bundles its own version of the listing grid, it’s called Toolkit > Listing Grid. Make sure to use the Listing Grid widget of the Toolkit plugin!
Using that widget, you can set the Listing Grid Find listings using option to Related Listings.
Then you can use the other widget options to set the number of columns.