It sounds like you were charged with a retail theft ordinance violation. "Forf. U." means "unclassified forfeiture," and that's how ordinance violations, traffic tickets, etc., appear in the court records. These are forfeitures, which means there is only a monetary penalty. Crimes, on the other hand, have the possibility of jail or prison.
A forfeiture is not a crime. I tend to liken it to a traffic ticket. The cop was right that it won't go on your criminal record. However, it will remain in the public records, so, if it's a circuit court case, it'll show up on wcca.wicourts.gov, or if it's municipal court, it would be in those records, which may or may not be online.
Wisconsin law allows businesses to sue people who steal from their stores. In my opinion, their lawyers send letters to intimidate people into paying. I generally tell my clients that the money is not owed unless a court says so, and that I've never heard of anyone being sued. I've attached a link to a very informative article about the topic.
Disclaimer: This is legal information; not legal advice, so don't rely on it. I'm a lawyer, but I'm not YOUR lawyer. If you need legal assistance, you should contact a lawyer licensed in your state.
A forfeiture (your ticket) is not criminal. However, your alleged actions (I don't know what you did) could conceivably be considered criminal. Theoretically, the prosecutor could decide to issue criminal charges instead of or in addition to the forfeiture ticket. Therefore, proceed prudently with the alleged victim, Kohls. I highly recommend you consult with an attorney as you decide how to handle.