Below is a quote from Klein's Organic Chemistry 3rd edition:
Here is the bottom line: Whenever an atom possesses both a π bond and a lone pair, they will not both participate in resonance
However, I am confused as a few pages prior it was shown how allylic lone pairs and pi-bonds participated in resonance:
The first curved arrow goes from the lone pair to form a π bond, while the second curved arrow goes from the π bond to form a lone pair:
What have I understood wrongly?