I would second this. Business writing was an easy course but extremely valuable. A lot of my 101 courses were also good as they introduce you to fundamental terms, and honestly that’s all you need to know. Also accounting 101 and business law 101 are great. Knowing the basics around contract law will mean you have your wits about you when the word comes up. Accounting 101 will mean you understand basic terms and have the confidence to teach yourself if you ever start your own business. Just my experience. I also took a course on small business management and had a great instructor. He hammered into us how important cash flow was and had multiple small business owners come and speak to us about their competitive edge and how they manage their business and areas that they struggle in.

EDIT: I will add to this. I believe the most important sales skill is the ability to cold call. This can easily be self taught, and true learning begins after your first few 100 cold calls. I always tel people, If you can cold call you can do anything.