It’s a common structure for purple especially. “_____ Something” or “Something ______”. It means that the connection is that each word/phrase in that category works if you fill in the blank with that word. So today’s is that “Attack Ad”, “Personal Ad” (aka “the personals” section of a newspaper), “Pop-up Ad”, and “Want Ad” (a term I’m not familiar with, but searching tells me it might be similar to a personal ad) are all phrases that exist.