This means that all artifact of your project including your dependency will be searched in this repo.
You could also have a glance at pom.xml to check if there was an effort made to deploy artifacts to a remote repo. Typically the keywords are oss.sonatype.org or raw.github.com like in this case.
It works because JitPack will check out the code and build it. So you'll end up downloading the jar.
If the project doesn't have a GitHub release then its possible to use a commit id as the version.
Another very nice thing about Jitpack is, it has a lookup button on the main page. And if you type the URL of your GitHub repository, it displays different commits of the source code, and you can select which commit/tag you want. The Jitpack creates pom dependencies for you.