What does this vehicle transport?
Your question is rather broad and somewhat unclear, but what you have is a picture of a baggage tug and cart. 

The carts are loaded with passenger baggage or cargo, then strings of them are pulled to the aircraft by the tug before being loaded on to the plane.

Based on the additional pictures, I think what you're after would be called palletized cargo. It's stuff, put in boxes, placed on pallets, wrapped with stretch wrap, with a net thrown over the top and hooked down to keep it from sliding off the pallet.

It is most likely not passenger baggage. That's either loaded one piece at a time by hand, or in a ULD.

If you're asking what's in those particular boxes, you'd have to zoom in quite close to find a label on a box to even have a chance of figuring it out. Just about anything can be and is shipped in a brown cardboard box, from anywhere to anywhere in the world. This question is far too broad and off topic for Aviation.SE, and probably any SE.