If you open the Excel within an Excel application scope activity you can use the attached example below, the “Index” 0 (zero, circled in green) will return in the string variable “SheetName” (outlined in green), the name of the first sheet.
@ron.butler I think I must be on a newer UI Path version as I do not have Excel Application Scope Activity anymore - just Use Excel File or Excel Process Scope. The Properties are different
You have a different Excel activities package loaded then the one I used, is all, try to use a search in your activities panel, using the key words one at a time or in combination Get Workbook Sheet, this may find the equivalent activity name for your Excel package.
Try using your For Each Sheet activity, you only have one sheet you say but that activity may not need a sheet name it may act on all sheets in the workbook regardless of name and should not matter if it only finds one sheet.