What does a high sgpt level indicate?

Liver inflammation. Sgpt is one of the enzymes (the other related one being sgot) produced as part of liver metabolism. If either are high, this indicates some problem with the liver causing inflammation such as alcohol, infection, gallstones, viral hepatitis, or a great many other things. Many times this is temporary but if your doctor discovers this, (s)he will follow up to make sure it normalizes.
Liver irritation. Can't be sure of cause. All depends upon your history / exam and a host of other lab work.