What does this key do on this laptop?

This key is designed to bring up Copilot if it's available on your PC. If not, it will default to opening Windows Search. Read more here if this is your personal PC: https://support.microsoft.com/en-us/surface/use-surface-pro-flex-keyboard-13566b78-8afe-493f-a7b8-ebc51efb6e20. If this is a work PC, your experience might be different: Evolving the Copilot key experience for commercial organizations - Windows IT Pro Blog.