The following actions will launch an excel file > set the active spreadsheet > read the value of the first cell (copy/paste in your flow):
Excel.LaunchExcel.Launch Visible: True LoadAddInsAndMacros: False Instance=> ExcelInstance
Excel.SetActiveWorksheet.ActivateWorksheetByName Instance: ExcelInstance Name: $'''Sheet1'''
Excel.ReadFromExcel.ReadCell Instance: ExcelInstance StartColumn: $'''A''' StartRow: 1 ReadAsText: False CellValue=> ExcelData
You should be able to retrieve the value by changing the 1st action so as to open your excel file and the name of the spreadsheet.
Note:
The 1st action will produce the variable you need for the following excel actions, it's an ID for the excel file you just opened (in case you open multiple files). In the above example, I left the default name %ExcelInstance%.
The 2nd action can be omitted if your excel file does not have multiple tabs. In case you use it, you'll need to provide the actual name of the spreadsheet and the correct excel instance from the 1st action:

The 3rd action will read the value from the A1 cell.