This feature can be accessed via the Administration Panel, (Penciil) > Administration > Site > Shortened URLs
When you browse to that location you should see something similar to the following:
Enter the URL you want to shorten and a quick description then click the Create button.
After that click on the View button and the platform will display the shortened URL.
It's worth noting that the platform knows how to redirect within itself regarding its own moved content, but doesn't support manually-defined redirects to or from outside the community. These redirects would need to be configured outside of community, potentially at the IIS level.