Hello,

There is multiple ways to do that.
First, you need to know that Google will judge the quality of an ad from its content. If the user doesn't fill the ad correctly or don't put enought infos, you will not be able to improve its presence.

But, you can improve the list page. The first thing to do is check the page title. It must be something clear that a human can understand, for example, if your title is 'cars' and you sell cars in a specific region, change it to 'Buy your car in {region}'.

Then you can also create a module custom and write a text describing the category. Then you can place this text above the list.

Best regards.

Hello,

Yes exactly.
The purpose of this module will be to display a simple text.

Best regards.

Hello,

You solution will work perfectly.
You just need to display a simple text, the method doesn't matter .

Best regards.