It'd be a ban of any mixture of vertical integrating with not vertically integrating. Which in turn makes it tough to transition (either direction) between the two.
So, Apple would be allowed to vertically integrate and make the chips, hardware, operating system, and applications for their products. But they'd have to stop selling Belkin chargers alongside Apple chargers at apple.com, and the iOS app store would have to contain either only Apple apps and no third-party ones or vice versa.
It fixes a power imbalance that allows for the platforms to take advantage of their customers. A platform becoming dominant is insidious because it takes away the "choice" ... if you want to do business, you will probably have to engage with them, but as we see here, Amazon is taking advantage of the fact that they own the platform by taking their customers' (the sellers) data, and using it for themselves to put their customers out of business.
So, Apple would be allowed to vertically integrate and make the chips, hardware, operating system, and applications for their products. But they'd have to stop selling Belkin chargers alongside Apple chargers at apple.com, and the iOS app store would have to contain either only Apple apps and no third-party ones or vice versa.