Apple - Is there a way in Numbers to flip columns with rows?

With the table selected, simply choose Table > Transpose Rows and Columns.

You have a one-year old question in Super User about this.
It links to an Apple forum page where you will be told to how to use INDEX and TRANSPOSE functions to achieve what you're looking for.
The Past Special of Excel is way easier but this function is not widely used so apparently dropped from Numbers.