Open "demo.html" to see a list of all the glyphs in the Linearicons-Free font along with their codes.
You won't need any of the files located under the "demo-files" directory when including the generated font in your own projects.
You can import "selection.json" to the IcoMoon app (https://icomoon.io/app) using the "Import Icons" button (or via Main Menu > Manage Projects) to modify or subset this font for further optimization.