Picture is posted...thanks...that is a RECEPTACLE and you use a PLUG to complete the connections.
On older coaches, you had to disconnect the shore cord and plug the end into that outlet in order to use the generator. In other words, look in that compartment for a short cord with a MALE end...a PLUG. Your shore cord would then be male and female....hope that makes sense.
Put another way, that receptacle comes FROM your generator. The short cord that plugs into it feeds everything in your coach. To use shore power, you unplug that short cord and plug your shore line into it.....Dennis