If  you want to update data in your mendix application with data from excel it could be done with

1. Implement the excelimporter from the marketplace, see documentation there
2. Create an entity with the columns from excel you want to read
3. Refresh model reflection (needed for step 1)
4. Create an import mapping from excel to the entity of step 2
5. Import the excel file with the mapping (either manually of by a microflow, see docs of excel importer)
6. Create a microflow like above, but iterate the lines read with step 5 and refresh or create your mendix  target objects, use a unique to find them
7. Delete the objects from step 5 or set an error status on them to be able to find data errors like missing fields and wrong values.

You can do this directly on your target objects but that is not recommended.