ive seen some posts where people say they tune to concert pitch 440 etc, wtf does it mean and what difference does it make if the hz is higher or lower (i know the number means hz but dunno wat difference it makes to the tuning)
and what is the most accurate setting
440 Hz is the standard reference pitch for tuning forks. The tone that occurs at 440 Hz is an A, I think one octave above middle C. Even if I'm wrong about that, it'll still be the same pitch that would occur on your high E string on the 5th fret. The open A string is 110 Hz.
Hi, I'm Peter
Its 440hz, which is a calculation of frequency. 440 is the frequency of an A above middle C in concert pitch 440 tuning. These days we use 440 regularly, but before, people used a bit higher and lower.

HZ is the calculation of frequency, and the higher/lower a frequency is, the higher/lower the pitch is.