A turboprop engine is an engine which drives and aircraft propeller. This engine’s exhaust gases, unlike a turbojet’s, don’t contain an amount of energy that could create significant thrust. That’s due to the fact that almost all of its power is used to drive the propeller.
In a single spool turboprop engine, the same spool that drives the compressor drives the propeller too.
In addition, a reduction gearbox reduces the spool rotational speed of the engine to accommodate the propeller because it needs to rotate at a lower RPM. Check it out!