Born on 20 December 1890 in Lodz, Poland. His father was a tinsmith. He learned in cheders and later became a clockmaker.

Due to his desire for the stage, he exploited the opportunity that he had due to his father working in the theatre, and so he arrived in 1908 as a stand-in in Zandberg's troupe. Then he debuted as "Bel khzkh" in Mark Arenshteyn's "Vilner bel-habitl." Sh. already remained there until 1912 as a episodic role player. Then he traveled to London, where he joined the troupe of M.D. Waxman. In 1913 he played in London in the troupe of Blumental-Waxman, and in 1914 in Vienna, Lemberg, and across the province.

After serving for three years as a soldier in the First World War, Sh. from 1918-20 was in Krakow under the direction of Tsolman. From here he traveled to Frankfurt (Germany), where he played for half-a-year under the direction of Mangel. In 1921 he played for three months with Fishelevitch in Berlin, then again with Blumental in Paris, and then he returned to Berlin. (Dir. Shtrobel), later with a member's troupe. He returned back to Poland, touring for a short time with his sisters Esther and Malka, Shlomo Kutner, Zalmen and Miriam Zylbercweig, across the Polish province with a "miniature theatre."

In 1923 Sh. played for a year in Buenos Aires, Argentina. In 1924 he was again in Berlin, in a member's troupe. From 1925 to 1927 he again guest-starred in Argentina, and then he returned to Europe, where he played in various countries, in 1929 with

Kompaneyets in Paris, in 1930 (director Blumental) in Belgium, and then before the outbreak of the Second World War in Paris, then returning to Belgium.

Zalmen Zylbercweig characterizes him this way:

"Shefner was an original type. I have, among Yiddish actors not seen them all. Such purity, such neatness that surpassed every imagination. He used to wear a coat very soon, and his appearance very much landed, dressed himself in life, even on stage, if the role required it for his 'amant' roles, exceptionally elegantly. Not only did he constantly, from act to act, also hit the soles. He was a very skilled dancer and a fine 'couplet' singer. His acting talent was not so specially shown, but later he actually took to the world as a star, in the first roles."

About his tragic end, his sister Malka writes:

"He played in Belgium, where he received a letter from Lodz from our father, in which he invited him, that when his mother was not alive, and he is old and doesn't feel well, that if he still wanted to see him, ask him to come home. That his dad really loved him. Yakov traveled to Lodz, perhaps six or seven weeks before the outbreak of the wear in 1939. He considered it a few weeks. While he was there he began to play theatre, and as such he remained there until the war broke out. I was surprised that he then was found in the province, I did not know what they were doing, but they all returned to Lodz. It didn't take long for the Germans to settle in France. At the beginning, they did not kill the Jews. I wrote to him, but I never received an answer. Until one time I met an acquaintance who told me that he got a message from Lodz, but through Italy, and he permitted me to write several words in his letter to my family. A short time later a friend brought us a small letter from my brother Yakov, who mentioned nothing about  my younger brother Moshe, but wrote that he and their father were going to live where their uncle lived (the father lived in the Old City), and from that I understood that they went over to the ghetto. A second time I again received a short letter from him, with the plea from him to send money. So as no one wanted to accept any money from me, I began to send him packages that they could sell or exchange. I received no reply. In the meantime, trouble has begun for us in France. Various new laws were being fled every day.

After the war I kept looking for my brothers. I gave up the old facts, because it was easy to understand that an old sick man would not be able to endure his troubles. Later, my brother, my only brother, Shmuel, who lived in Frankfurt, wrote to me about the beautiful years, when he realized that Jacob and his father had gone hungry in the Lodz Ghetto."

M.E.
Sh.E. from his sister Malka and Zalmen Zylbercweig.