"After Effects error: Crash in progress" I NEED HELP PLZ

Welcome to the community, Bob.

Please share the following details if After Effects keeps crashing:

• When does it crash? Is there a specific action/command that triggers it? 
• Do you see any crash reports? If so, provide your email ID to the crash reporter and submit it.
• What are your system specifications (CPU, GPU, RAM, OS version)?

We're here to help, just need more info.

Thanks,

Nishu

It means that AE is crashing. Presumably after you dismiss that dialog, AE will crash and disappear. You're perfectly safe to relaunch and keep working, but if the issue keeps happening, then you need to start troubleshooting to figure out what's causing the crash.