Like ads trying to raise money for charity - not for profit ads basically. You can always tell PSAs because they actually say Public Service on them. They're also incredibly unattractive on the eye - black and white.
Public Ads they are adsense placed by Google for non profit organizations , and google do not pay you for any click on these ads ? why do you see these ads on your page ? when google Algorithm and system falls to check any relevant ads to your web page contents these ads are placed ! ao try to do something with your content try to use headers, change the title of the page , meta tags description , make some topics bold etc