As you can probably tell by the name, iCloud+ is Apple’s cloud service. For years, it was just called iCloud across both the free and paid tiers, but more recently, Apple has added a set of premium features to encourage free users to subscribe.
For starters, you can get anywhere from 50GB to 2TB of cloud storage, depending on the plan you choose. However, now there are also a lot of security features available too, like iCloud Private Relay, which hides your IP address and browsing activity, and Hide My Email, which will create a random email address that you can use to receive email without having to give away your own personal one.
With all that said, you still get 5GB of cloud storage for the free version, so if you don’t need more storage and don’t want all the advanced security features, you can still sync your iPhone and other devices with iCloud without paying a penny.