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/.
5:57PM BST 15 Apr 2014. The iPhone 5S has been crowned the most durable flagship mobile handset in a set of rigorous durability tests. Pitted against the newly-released Samsung Galaxy S5, HTC One (M8) and the LG Nexus 5, the iPhone 5S was deemed to be the handset most likely to survive numerous hazardous situations.