What does ,err do?

For the following request, what does the , err do?

data_grid, err = ek.get_data(['IBM', 'GOOG.O', 'MSFT.O'],
                             ['TR.TotalReturnYTD', 'TR.WACCBeta', 'YRHIGH', 'YRLOW'])

I notice when keeping ' ,err' the dataframe is displayed in a nice format in my Jupyter Notebook whereas without it looks to be formatted in a tuple or something. Any explanation would be much appreciated. Thank you.