To know what the light means, you need to:
1. Describe the light: Is it a solid light? Flashing? What color is it (red, yellow/amber, etc.)? Does it have a symbol (e.g., a tire, an engine, a warning triangle)? A picture would be extremely helpful.
2. Consult your owner's manual: The owner's manual for your specific year and model Chevy Trailblazer will have a section explaining all the dashboard warning lights and their meanings.
Once you provide more information about the light itself, I can try to give you a more accurate answer. The "bolt on side rear" detail is not a standard automotive terminology and likely refers to something specific to your vehicle's situation (maybe a recent repair or modification).
