Trying to import and I keep getting an error about invalid "" columns I looked through the entire sheet to see maybe if there's a character somewhere..
Open the file in a text editor and save it as UTF-8 encoding.
Also if you are using Import/Export > Import, make sure that you have all the required by Magento fields and column names should be identical as database names (otherwise that might be simply not recognized).
Use export to have example of column names or check this tutorial on required columns and header names for CSV import -
Hope this helps.