Based on both the user manual and the service manual for the RF260B***** series (which includes the RF260BEAESR):
The water filter is located inside the main refrigerator compartment, positioned between the two vegetable and fruit drawers at the bottom.
You’ll need to open the refrigerator doors to access it. It’s typically a long, cylindrical cartridge that you twist to unlock and then pull out.
For the water filter location of other Samsung refrigerator models, see