Villi / capillary network

Why does 1 side of the capillary network in a villus contain more oxygen than the other side that has more carbon dioxide?

Think about the role of oxygen in blood. Then think about the role of the capillaries. It's mainly to do with the role of the capillaries (I know you've given the example of a villus, but ignore nutrients, just the oxygen and carbon dioxide concentrations. It may be easier for you to think of a more typical example which is a capillary supplying part of a muscle

ahh, so would the oxygen be used up by the villi for respiration and that is why one side is oxygenated and the other is full of co2 ,no?

Yep, capillaries are great at letting diffusion take place, so (some) nutrients enter the blood there, as well as oxygen diffusing out of the blood to be used in aerobic respiration. The carbon dioxide produced from this respiration is also taken up into the blood so that it can be breathed out by the lungs

Not sure which level you are at, but worth knowing why it is that capillaries are good for letting diffusion happen