@zxcnice2332 This means none of the seeders are able to upload any piece of the torrent to your client because they are disconnected at the moment or because there is no seeder at all, meaning the torrent is dead. If you check the torrent page and it shows that there is at least one seeder, then you just need to keep your app running and eventually it will start to download, it might even take days.
Just to clear any confusion, the availability indicates which pieces YOU have available for other people to download from, if it's all red that means you don't have any, and that is a consequence of not having anyone actively seeding at the moment.