A few months back, BitTorrent managed to get a lot of its users up in arms by announcing that uTorrent will start featuring ads. BitTorrent needs to make some money, but people were obviously annoyed at the idea of having ads inside their app.
The backlash got to BitTorrent who backed down and promised to make the ads optional.
It seemed like a worthwhile compromise, but now that ads have actually made their way into the client, it seems that the option to remove them is a bit too complicated for most people.
The ads, which promote various software, like Facebook Lite for Desktop - not an official app, are made to look somewhat like a regular torrent would.
But they are separated from the active torrents list and have a yellowish background, like Google's search ads, which should make them different enough for people to realize they're ads.
Still, if you don't like them, there is a way to get rid of them. Go to Options > Preferences > Advanced and find "offers.left_rail_offer_enabled" and "offers.sponsored_torrent_offer_enabled." Set them both to "false" and you're done.