A Serious Man contains a lot of Jewish/Yiddish words, here's a handy glossary;

Agunah (pronounced “ahgoonah”) – a divorced person who has not been religiously sanctioned to remarry.
As in when Judy says, “Without a Gett I'm an Agunah.”

Bar mitzvah – Jewish religion's important ceremony, held in a  synagogue for a young man who has come of age (at 13) and will now be responsible for practicing and upholding Jewish values, morals, and traditions; female equivalent (at 12 or 13) is a  bat mitzvah .
As in when Larry says, “But I'm so strapped for cash right now—carrying the mortgage and paying for the Jolly Roger, and I wrecked the car and Danny's bar mitzvah coming up…”

Bupkes (also spelled  bupkis ) – nothing; applied with great emphasis.
As in when Arthur says, “You've got a  family . You've got a  job .  Hashem hasn't given me bupkes .”

Chacham (also spelled  chakham ,  hakham or  haham ) – a wise or learned man, usually a great  Torah scholar.
As in when the Man says, “You know, Reb Groshkover! Pesel Bunim's uncle! The  chacham from Lodz, who studied under the Zohar reb in Krakow!”

Dybbuk (pronounced “dibbuck”) – The soul of a dead person, often looking to possess a live person and as such inspiring fear among the living.
As in when Reb Groshkover says, “I shaved hastily this morning and missed a bit—by you this makes me a dybbuk?”

Gett – ref.,  agunah (above); a religiously sanctioned divorce, tandemed with the sanction to remarry.
As in when Judy says, “Esther is dead three years. And it was a loveless marriage. Sy wants a Gett.”

Goy – colloquial term for a person not of the Jewish faith (i.e., a Gentile)
As in when Rabbi Nachtner says, “Do you know a goy named Kraus? Russel Kraus?”

Haftorah – Portions of the Hebrew Bible read aloud in synagogue services, including by a  bar mitzvah boy.
As in when Larry says, “How's the haftorah coming? Can you maybe use the hi-fi?”

Hashem – means The Name, and is basic Hebrew term/name used for God.
As in when Rabbi Scott says, “I too have had the feeling of losing track of Hashem , which is the problem here. I too have forgotten how to see Him in the world.”

Kabballah (also spelled  caballah or cabala ) – an interpretation of the Scriptures based on an oral tradition that supposedly began with Abraham.
As in when Rabbi Nachtner says, “But Sussman is an educated man. Not the world's greatest sage, maybe, no Rabbi Marshak, but he knows a thing or two from the Zohar and the Caballah.”

Macher (pronounced “mohhcc-er”) – an achiever, a person of importance/influence.

Mazel tov! (pronounced “mozzle-tov!”) – Congratulations!
As in when the Doctor says, “Well,  mazel tov . They grow up fast, don't they?”

Mensch (pronounced “mensh”) – someone with strength of character/an applied sense of purpose.

Mitzvah – good deedor blessing, though mostly used in an everyday and non-religious context.
As in when Reb Groshkover says, “One does a  mitzvah and this is the thanks one gets?”

Nu? – What's up? What's the story here?
As in when the Principal says, “Hmm… eh… nu?”

Rabbi (pronounced “rab-eye”) – Ordained Jewish religious scholar/teacher, often relied upon as community leader.
As in when Judy says, “I have  begged you to see the Rabbi.”

Reb – Formal-address equivalent of Mister.
As in when the Man says, “I assure you, Reb Groshkover, it's nothing personal; she heard a story you had died, three years ago, at Pesel Bunim's house.”

Shabbas (or,  shabbos , from  Shabbat ) – Judaism's Sabbath, from Friday evening through Saturday evening
As in when Rabbi Nachtner says, “Danny Gopnik, the Sisterhood makes a gift to you of this kiddush cup so that you will remember this blessed day on the next shabbas and the next, and on every shabbas of a long and fruitful life…”

Shtetl (pronounced “shtet-el”) – a small Jewish village, in bygone times, in Eastern Europe.

Shiva – means seven, and also refers to the participatory seven-day mourning period for the recently deceased.
As in when the Wife says, “Traitle Groshkover died of typhus in Pesel Bunim's house. Pesel told me—she sat  shiva for him.”

Shul – a  synagogue and its congregation.
As in when Rabbi Scott says, “Because with the right perspective you can see the  Hashem , you know, reaching into the world. He is in the world, not just in shul.”

Synagogue (pronounced “sinagog”) – a Jewish house of worship.

Torah – the first five books of the Hebrew Scriptures, transcribed onto a scroll for use in  synagogue services including a  bar mitzvah .
As in when Rabbi Nachtner says, “Is the answer in Caballah? In Torah? Or is there even a question?”

Zohar – the main text of  Kabbalah , the Zohar is a mystical interpretation of the  Torah .
As in when Rabbi Nachtner says, “ He knows a thing or two from the Zohar and the Caballah.”