There is nothing in that code statement that is actually right!
num1 === typeof(number)
Should be
"number" === typeof(num1)
And the same for
num2
The operator test: you can't write it like that: "-" is not a condition, nor are "*" or "/"
You would need to compare each item separately:
(sign === "+" || sign === "-" ... ){
You then identify that sign is a operator, but try to assume it's an integer by parsing it.
Then instead of working out the operation, you try to return three values - which Javascript won't let you do ...
THrow the whole lot away, sit down and think about what you are trying to do: that looks like you skimmed your lesson, skimmed the homework question, ignored what you should know about Javascript and threw some random junk down in the hope that we would do the work for you ...