The FSR points to any of the other file registers and allows you to read or write the value of the register it points too by reading or writing the IND register.
e.g. if the FSR points to the Status register, and you mov w, ind, the W register now contains a copy of the status register. More useful examples would include buffers, FIFOs, stacks and other multi register constructs.
Keep in mind that loading the FSR sets the bank (were not in bank 0 anymore toto...)
See: