How do you replace a left rear turn signal light on a 2001 Blazer?

For any Gen II (1995 - 2005) Blazer, Jimmy, or Bravada, it's all the same.

Open the hatch. On the side of the door jamb, you'll see two screws - those hold the tail lamp assembly in place. Remove those, and the whole tail lamp assembly will come out. The bulb holders are in the back of the tail lamp assembly - rotate them counterclockwise, and they will come out. Then you can replace the bulb, put the lamp holder back into the tail lamp assembly, and the installation is the opposite of removal. Pretty simple stuff.. only tools required are a short Phillips screwdriver.