If you received a Form 1099-MISC instead of a Form W-2, the payer of your income did not consider you an employee and did not withhold income tax or Social Security and Medicare tax. This income is considered self-employment income and you must complete Schedule C (or Schedule F) and Schedule SE.
Incorrectly reporting this income: If you were to just report the income as "Other Income", these additional taxes would not calculate correctly. When the IRS reviewed your return later in the year, they would find that you did not report this correctly and you would have to not only pay the self-employment taxes, but you may end up owing penalties and interest.
Here is an overview article that can help you understand the schedule C and self-employment.
https://turbotax.intuit.com/tax-tips/self-employment-taxes/reporting-self-employment-business-income...