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 sixth generation of Apple's immensely popular iPhone mobile smartphone. The iPhone 6 made its official debut in September 2014, following the iPhone 5S as the company's latest, greatest smartphone device.