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/.
iPhone (1st generation) This is the latest accepted revision, reviewed on 12 April 2017. The iPhone (unofficially referred as the iPhone 2G), is the first smartphone model designed and marketed by Apple. It is the first generation of iPhone that was announced on January 9, 2007 after years of rumors and speculation. It was introduced in the United States on June 29, 2007, and it featured quad-band GSM cellular connectivity with GPRS and EDGE support for data transfer.