Medium is required by law to report all royalty earnings over $0.50. This form is a summary of what you earned for the previous tax year and to show you what we will be reporting. In most cases, you do not need to do anything further for US taxes.
Medium is not tax professionals and not able to advise you on how/when to file your taxes. Because everyone's situation is unique, you may want to contact your local tax professional for more information or assistance on reporting and filing for your country.