It's native ARM version of Windows 10 and for UWP apps, as well as any x86 apps recompiled for ARM. The rest of the classic x86 32-bit apps will run via the emulation, like Rosetta on macOS in the past when running PPC apps on Intel.
That means unlike WinRT, almost all of your apps will be usable, no confusion about it like what befell the WindowsRT.
That means unlike WinRT, almost all of your apps will be usable, no confusion about it like what befell the WindowsRT.