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/.
Apple is widely expected to announce a new iPhone on Wednesday (September 9, 2015) and speculation is that it will keep the world's most popular smartphone on a lofty perch. The Apple iPhone 6S release is expected on September 9. The new phone's on sale date should follow soon after.Apple.