The only one i know is pH and i know the is the acidity level and i think 7 is neutral but what are the others?

You're quite right about pH - 7 is neutral; less than 7 is acid and more than 7 is alkaline. The pH scale is logarithmic, meaning that each unit change in pH, say from 7 to 8, is a 10 times change: a pH of 8 is therefore 10 times more alkaline than 7.

The other common abbreviations used in fishkeeping are:

O2: oxygen
CO2: carbon dioxide
Cl2: chlorine
GH (or dGH): general hardness of water
KH: carbonate hardness of water (also sometimes calledthe water's 'buffering capacity', meaning its ability to maintain a stable pH level)
NH3: (free) ammonia
NH4: ammonium
NO2: nitrite
NO3: nitrate
RO: reverse osmosis (treated water)
UVC: ultraviolet clarifier
UVs: ultraviolet steriliser (NB: these two are not commonly used in coldwater fishkeeping - they tend to be used in marine tanks)
UGF: undergravel filter

I think I remembered them all! Need any further info. about any of these?

I think that just about covers it. thanx!