tjkoko- there is a chain guard on that bike, but the OP is asking about the fact that the entire drivetrain is in fact on the left side of the bike. for this to work, the crankset and the rear hub are designed to accommodate a LHD (left hand drive) system. the sprocket locator bolt is on the left crank arm, or on both the left and right. the hub engages when the driver is spun anti-clockwise and only works on a LHD-specific hub.

I wrote a tech article for BMX riders some time ago. some of the information is a bit dated but this gets the general idea- bicycle necromancy: left-hand and right-hand drives