A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Most importantly the Excel file must be saved in one of the current Excel file types: .xlsx, .xslm. etc The older binary file types [.xls. etc.] do not support the Sparklines feature.
The feature is a separate group on the Insert tab immediately to the right of the Charts group.
This may help: support.microsoft.com › en-us › officeUse sparklines to show data trends - Microsoft Support
If you don't see it please go to Excel> About Microsoft Excel in the main menu to determine the specific Version & type of License for your Office software. Include that as well as your version of macOS in your reply.