The equals sign means is equal to. It is telling us that one thing equates to another; that they are the same.
The iPhone 4 is the most recent iPhone to be discontinued from the iOS Update cycle. It did not receive the iOS 8 update, so it's final software version is iOS 7.1.2. You can update to this version through iTunes, or download it from an IPSW repository like this website: https://ipsw.me/.
The current 4.7-inch iPhone 6 and 5.5-inch iPhone 6 Plus are the best-selling iPhones yet so they will likely be updated when the iPhone 7 release date rolls around. So if this latest report is true then we could see three new iPhones released in 2015.