What did you try so far?
* Did you check the links in the box "similar threads" below.
* did you do an internet search? --> https://lmgtfy.com/?q=asic+spyglass+check
* did you consult the manual or the software manufacturer?
This is just the simplest answer: Spyglass is for doing Lint checks for an RTL code.
For any detailed info you can always refer to Spyglass documentation.