what is itunes connect?

Welcome to Apple Support Communities

iTunes Connect is a website that developers use to upload their content to Apple to make it available in the App Store, the iTunes Store, iBooks Store or the Mac App Store. This is the iTunes Connect website -> https://itunesconnect.apple.com/WebObjects/iTunesConnect.woa

Also, have a look at this site -> https://developer.apple.com/support/itunes-connect/