With Microsoft's launch of the Surface Pro X last week, questions were once again raised about the apps that can run on it. The answer is that like any Windows 10 on ARM PC, it can run native ARM (ARM and ARM64) apps, and it can run emulated 32-bit Intel (x86) apps.
This leaves out 64-bit Intel (AMD64, or x64) apps, so if you want an app that's only available in an x64 flavor, such as Adobe Premiere Pro or Photoshop Elements, you can't use it.
That's going to change though. Speaking with several sources, I can confirm that Microsoft is indeed working on bringing x64 app emulation to Windows on ARM. When that will happen is a bit more unclear, but it seems like it could be in Windows 10 21H1, which would mean that the general public will have access to it in the first half of 2021, and Windows Insiders will be able to test it out next year.