You will either have to 'SHIFT + right click' the file and use "Open With..." and the find excel, or open in
from excel using the File ---> Open button. The file extension
'.radios' is not registered to excel in your registry, so excel will not default to open it.
as
@slicerwizard stated, it is a comma separated values file (CSV) but it is not registered with the OS as a file with a .CSV extension.