Drivetrain or Powertrain Warning
One of the most most complex part of your car is the drivetrain and powertrain.
The drivetrain generally refers to everything after your car's engine, such as the transmission, driveshaft, and axles. The powertrain is usually referring to your car's engine system. Another word you may here used in conjunction with this is the valvetrain, which refers to the valves, rockers, and camshaft of the engine. Each of these 3 systems is comprised of many smaller intricate parts crucial to your vehicle's proper operation.
You will often hear the terms drivetrain and powertrain used interchangeably, and both can mean the entire system that makes your car move, from the engine to the transmission's output. If you see this indicator light come on in your car, you should take it very seriously, as these parts are extremely complex, and can result in very costly repairs.
Generally, this indicator light means a problem has been detected in the automatic transmission (not applicable in manual transmission cars) or transaxle. This light can also indicate an Electric Shift Control system warning.
There is not very much in the powertrain or drivetrain that the average person can fix on their own, so you will likely need a professional with specialized equipment and knowledge to resolve these issues.
Some cars also use this light to indicate an engine problem, but in most cars, that Check Engine light is reserved for that.