Assuming that by "file" they mean "regular file", as opposed to directory, symbolic link, socket, named pipe etc.
To find all regular files that have a filename suffix
.xls and that reside in or below a directory in the current directory that contain the string
SCHEDULE in its name:
find . -type f -path '*SCHEDULE*/*' -name '*.xls'
-type f we test the file type of the thing that
find is currently processing. If it's a regular file (the
f type), the next test is considered (otherwise, if it's anything but a file, the next thing is examined).
-path test is a test agains the complete pathname to the file that
find is currently examining. If this pathname matches
*SCHEDULE*/*, the next test will be considered. The pattern will only match
SCHEDULE in directory names (not in the final filename) due to the
/ later in the pattern.
The last test is a test against the filename itself, and it will succeed if the filename ends with
Any pathname that passes all tests will by default be printed.
You could also shorten the command into
find . -type f -path '*SCHEDULE*/*.xls'