Excessive hours are credit hours taken in excess of what is required for the eventual undergraduate degree. In my case, I started my college education in 2003, so I am "grandfathered in" on the excess credit hour surcharge.
In the US, most states charge a fee that could be 50-100% of the actual tuition rate, in addition to the tuition and fees being paid by the student for classes registered once they exceed the number of hours allowed for them to complete their undergraduate degree. In Florida, students who started in 2011 & 2012 are allowed 115% of their required hours (usually 120, but allowed up to 138), but anything exceeding that is charged a 100% fee on top of tuition. I found that Texas & Arizona also have this rule. You can check under the registrar page of the college you are attending to see if this applies to you.
Federal financial aid maximums apply as well, limited to 180 attempted hours for an undergraduate degree.
The bolded does include withdrawn classes.