With PP and Excel open, create a new slide.
In Excel select the range of cells to display, add borders / format cells as required (default borders will not be copied).
Copy the selected range.
In PP, from the Menu select 'Edit' then 'Paste Special ...'
In the dialog box that opens select 'Microsoft Office Excel Worksheet Object'
If you also select the Past Link button, the PP range or chart will update when changes are made on the source worksheet.
The range of cells from the worksheet is now in your PP presentation, and can be edited in place - right click and select 'Worksheet Object' then 'Edit'.
Note that embedded excel worksheet ranges and Charts may include additional data in your PP presentation that is not visible on the slides, but can be accessed by others who you send the PP presentation to, by using the Edit function.
You can use the Edit - Paste Special ... approach to paste a picture of your data directly - no need for any intermediate steps. Select the dialog box option 'Picture (Enhanced Metafile) instead of the Worksheet object. Picture quality is pretty good, and AFAIK no extra data is transferred with the picture.