To prattle is to go on and on about something unimportant. Some people don't like your constant prattling about your collection of Lego figurines — but you're convinced it's the most fascinating topic on the planet!
Prattle can also be a noun. If your little sister won't leave you and your friends alone, you might complain to your parents about her constant prattle. And the constant prattle of the person in the next seat might make it difficult for you to nap on that long airplane trip. There are a lot of funny-sounding words with a meaning similar to prattle: chatter, blether, blather, jabber, gabble, blabber, and babble, to name a few.