You cannot open a spreadsheet as if it is a text file. What you are seeing in the program editor are just the binary bytes of the file interpreted as if they were text.
You can import an XLSX file into dataset(s). There is a GUI tool for that (not the Explorer tool you are using). But it is generally easier to write the code yourself. For example just create a libref using the XLSX engine pointing to the file. Then you can read each sheet as a dataset. To copy all of the sheets to dataset you might want to just use PROC COPY.
libname in xlsx '....\Customer_loan_data.xlsx' accress=readonly;
proc copy inlib=in outlib=work;
run;