Hello Asbaat, welcome to the forum. Looking at your screen you're obviously jail broken (love those icons!). So I'll move you over to the iPad Hacking Forum where you'll be among like enthusiasts with a possible answer.
Regards, Andrew
At a guess, it probably has something to do with app updates available or in the process of downloading. It's not a standard iOS icon, so it's probably related to Cydia or some other tweak.