I find this phrase often gets over-applied to situations where people are actually attempting to do something about a problem they feel passionate about.

To me, it's mostly straightforward: if you're actually following your words with meaningful action that could directly impact the problem, it's not virtue signalling.

Proposing meaningful gun regulation after a school shooting? Not virtue signalling. Offering thoughts and prayers and trying to put prayer back in schools? Virtue signal. That does nothing to resolve someone shooting people at a school.

It's also aggravating to see people start charities or donate their time and money towards a cause only to be accused of virtue signalling.