What is schedule C? The explanation makes no sense to me.

[xmasbaby0]

Schedule C is the schedule on which you show your business expenses if you are self-employed.    Do you have a 1099NEC?  Did you work as an independent contractor?

https://ttlc.intuit.com/questions/1901340-where-do-i-enter-schedule-c

https://ttlc.intuit.com/questions/3398950-what-self-employed-expenses-can-i-deduct

Here is what a Schedule C looks like:

https://www.irs.gov/pub/irs-pdf/f1040sc.pdf