The installer sets this variable to the full path of the 64-bit Program Files folder on the target system on 64-bit Windows versions. On 32-bit versions, this variable refers to a non-existing folder. However, the folder will be created automatically if you install files in it. The 32-bit Program Files folder is available as ProgramFilesFolder; the native version of the Program Files path is available as ProgramFilesXFolder.
You can refer to this variable as <ProgramFiles64Folder>. Do not change its value; it has been carefully configured for cross-platform compatibility.