There is a pin on the ESC connector labeled “TLM”. Connect it to a serial port and configure the serial port. Of course there is a Wiki for that. The above parameter BDMASK will give you Motor RPM to drive the harmonic notch filter, something else you will have to configure, but ESC telemetry can still be useful. The ESC also has a “Current” pin. Did you connect that to the FC for current monitoring?
W/o context this is meaningless.