The photo depicts a Somali "technical."
A "technical," as defined by the Jamestown Foundation's Global Terrorism Analysis, is "an armor-plated pick-up truck [or other such vehicle] equipped with an anti-aircraft gun, used for firepower and battlefield mobility."
During the time of Operation Restore Hope, Somali insurgents heavily used technicals - even in Mogadishu. Today, however, their use has been "largely abandoned...in urban Mogadishu..."
Photo, courtesy C.B. Stevens' Photo Collection of Somali Technicals.
Information, and quotes, from the Jamestown Foundation's "Global Terrorism Analysis" web site.