In this sentence, the word "put" means "used" or "applied". The sentence is saying that if a commodity (a product or resource that can be bought or sold) could only be used for one specific purpose and not for anything else, then there would be very few problems or complications. For example, if a commodity like wheat could only be used for making bread and nothing else, then there would be no confusion or difficulty in deciding what to do with it. But in reality, most commodities can be used for multiple purposes, which can create challenges in determining the most efficient or profitable way to use them.

Put here is a part of an idiom "put (something) to use" - to apply, to utilize in an effective way. For example, "After completing the course I was looking forward to putting my new skills to use"