Mah nishtana are the first two words in a phrase meaning, "why is tonight different from all other nights?" which begins each line of the four questions derived from the Mishna, Pesachim 10:4 traditionally asked by the youngest child attending a Passover Seder.
The four questions in transliteration:
Ma nishtanah halailah hazeh mikol haleilot? Sheb’khol haleilot anu okhlin umatzah; halailah hazeh, kuloh matzah. Sheb’khol haleilot anu okhlin sh’ar y’rakot; halailah hazeh, maror. Sheb’khol haleilot ein anu matbilin afilu pa’am ehat; halailah hazeh, shtei f’amim. Sheb’khol haleilot anu okhlin bein yoshvin uvein m’subin; halailah hazeh, kulanu m’subin.
The four questions translated to English:
Why is this night different from all other nights? On all other nights we eat leavened products and matzah, and on this night only matzah. On all other nights we eat all vegetables, and on this night only bitter herbs. On all other nights, we don’t dip our food even once, and on this night we dip twice. On all other nights we eat sitting or reclining, and on this night we only recline.
