Short answers, pulled from the story.
Kazimir Malevich was a Russian avant-garde artist and art theorist born in February 1879 near Kiev to an ethnic Polish family. He pioneered abstract painting in the 20th century and founded Suprematism, a radically non-objective form of painting he introduced in 1915. He died of cancer in Leningrad on the 15th of May 1935, at age 56.
Suprematism is a system of pure geometric abstraction on monochromatic grounds that Malevich introduced in 1915. He saw it as a way to access a higher, more pure realm of artistic expression and to tap into the spiritual through abstraction. He set out his theory in the brochure From Cubism and Futurism to Suprematism.
Black Square is Malevich's best-known Suprematist work, a black quadrilateral on a white ground first shown at the Last Futurist Exhibition 0,10 in Petrograd in 1915. He hung it in the upper corner of the room, echoing the spot reserved for icons in Russian homes. The first version now hangs at the Tretyakov Gallery in Moscow.
Kazimir Malevich was born near Kiev, in modern-day Ukraine, in February 1879 to parents who were ethnic Poles. Most academic literature identifies him as a Russian painter, but his nationality is disputed, and he has also been associated with the Polish and Ukrainian avant-garde. In a 1926 visa application he claimed Polish nationality, while a 1930 police file recorded him declaring Ukrainian nationality.
Malevich was arrested and interrogated by the OGPU in Leningrad in autumn 1930, accused of Polish espionage and threatened with execution. He was released in early December. Under Stalin, abstraction was condemned as bourgeois art, many of his works were confiscated, and he was removed from his teaching position.
Malevich's Suprematist Composition of 1916 sold at Christie's New York in May 2018 for over 85 million US dollars, a record auction price for a Russian work of art. The same painting had earlier set a record selling at Sotheby's in New York in 2008 for just over 60 million US dollars.