A Cause is a fund or area that you are raising money for (Building Fund / Tithes / Missions / etc).
A location is classified as an extension of your organization (multi-campus for example).
In order for a cause to be considered active (and show up as an option for your donors to give to), it must be assigned to the appropriate location. In the image below, the location name is Main, so the box next to Main will need to be checked in order for the the cause to be active. You may definitely edit the name "Main" (it's just a general name that we gave it) to reflect the needed location name.