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/.
On Tuesday, Apple unveiled three new smartphones of this year. iPhone 8 and 8 Plus are the traditional successors of iPhone 7 and 7 Plus but Apple blew minds away by revealing the 10th Anniversary iPhone aka iPhone X.