The Proscon Arc2 Lectern features 2 x female XLR sockets to suit 2 x standard lectern microphones (such as the Shure 412 or Audio Technica 49QL), on a 70cm wide top base.
Alternatively you can use one socket for a microphone, and the other for a light.
In most cases, you only need one microphone. However, the second is available for redundancy purposes. Microphones will require phantom power via XLR.