مش equal NO in slang words. Fusha is the mother language but each country has it's own slangs like بالزاف meaning alot but we don't use these word in egypt cause it'snot our culture .

مش = This word means ..(Not so ) or (not ) in the Arab-Egyptian But not used in classical Arabic عش = Nest

aww i get it now :) thanks everyone for your answer. It was helpful for sure :) God bless you !!

مش and عش both means "not" and the dialect and fusha are differents in accents: and also interms of vocaburaries aswell.

in sudanese مش means (right?) , and it is good to know there are big differences between slang and fusha..so i think you should learn fusha first because it is the original and each Arab country has own slang words.