Info about phase testing with a steinel combi checker

[john102956]

Hello. Recently used a steinel combi checker 1.2 to test various electrical items. Im ok with the voltage, continuity and single phase testing. However, i am not sure as to what phase testing is supposed to shows. According to the steinal guide it says"To perform the phase test, contact the small test probe with the phase(>90 AC) of the voltage system . The 6v step indicator (+and -) will light up phase contact". Although i have done the test what is the significance of (>90 AC)? Also, what does the 6v step indicator signify?
Thank you for your help.