A family of Microsoft word processing software products for creating web, email, and print documents.
If you are running Big Sur or earlier, Microsoft has reduced Office to view-only status. Here is Microsoft's page announcing their abandonment of users on older Macs, with disingenuous advice about upgrading your macOS version: Update Microsoft 365 or Office on your macOS or iOS device
As alternatives to Office for Mac under Big Sur, you can use Word for the web or Google Docs. Both of these are underpowered
For desktop software, with more capabilities, take a look at open-source LibreOffice, which has good compatibility with Office file formats.