The oil pan is leaking and smoking.
Oil leaks are common especially as vehicles get older. The smoke you see/smell is from the oil falling on hot metal from the engine running. As the oil burns off you see the smoke and get the odor. Once we realize we have an oil leak, it is important to keep an eye on our oil level. A big enough leak will run our engine dry and in severe cases could cause a fire. I would suggest getting a mechanic to inspect the oil leak. Some oil pans are pretty simple to repair and some require the engine to be lifted and the components to be removed. A mechanic, such as one from YourMechanic will be able to tell you what the repair will entail.