April Fool! There is NO word like Pushpash.
OK I'm technically wrong. Pushpash is no word, but Khushbaash does sound like 'pushpash' many times in the song 'Aane waala pal jaane wala hai' so if you're here looking for that meaning, well, the word is khushbaash, which means 'khush raho' in Hindi, and in English, would translate to 'remain happy'.
And so the line 'khushbash main chali' is 'Khush raho, main chali' or 'remain happy, I take your leave.'