Complex sentence: Les Kurbas (Ukrainian Олександр Степанович Курбас, 1887-1937) was the most important Ukrainian theater director of the 20th century and formed together with Vsevolod Meyerhold, Yevgeny Vakhtangov and several other directors the Soviet theater avantgarde in the 1920s and 30s.
Split into simpler sentences: Les Kurbas (Ukrainian Олександр Степанович Курбас, 1887-1937) is considered by many to be the most important Ukrainian theater director of the 20th century. He formed together with Vsevolod Meyerhold, Yevgeny Vakhtangov and several other directors the Soviet theater avantgarde in the 1920s and 30s.