By the GPWS = Ground Proximity Warning Computer ()?
I think not.
More likely from a Central Warning System Computer.
In general, 'T' represents temperature, 'N' shaft rotation speed and 'L' Low Pressure. The number 6 would be Stage 6 so we have a warning concerning Stage 6 Temperature and the LP shaft speed. Possibly a compressor surge. I say 'in general' but unfortunately the actual acronyms used in different aircraft electronic systems are getting very type oriented these days.