dlangschied, great question.
I ran into same problem when learning sql when importing from excel.
Look at column sql is reporting the error when importing.
Then go into excel, create a temporary column and use the len function, for example =len(a1), this will give you the lenght of the characters in the column.
Then sort by greatest to least, and you will identify which columns are greater than 255 character length in excel.
Chances are you're having some bad data garbled up in one cell in excel, thus causing this issue in when importing.
what you can then do is, either remove this data from excel then ones over 255, or what i do is
basically saying, use first 255 characters in excel for this cell, if you do this you won't run into any errors when importing in sql
hope this helps