That means no testing the system security, even as a favor to system management. No password sharing. They don't need your account except to damage your data storage or your good name. Non-university folks shouldn't be allowed to use what students have paid for. No commercial use.
State law prohibits the use of university resources for commercial gain.
Such a use, subsidized by taxpayer funds or student fees, would give an unfair advantage over competing commercial ventures that are paying for their own computer resources. You cannot use your access to make money. Internet Service Providers in the community are glad to sell you the computer access you need for your commercial endeavors. Respect the privacy of personal information. Respect for intellectual property.