Short answers, pulled from the story.
Yaroslav the Wise, born around 978, was Grand Prince of Kiev from 1019 until his death on the 20th of February 1054. He was a son of Vladimir the Great and previously served as Prince of Rostov from around 987 and Prince of Novgorod from 1010 before seizing the Kievan throne after a four-year civil war against his half-brother Sviatopolk.
Yaroslav the Wise built Saint Sophia Cathedral in Kiev in 1037, promulgated the Russkaya Pravda, the first legal code for East Slavic lands, and appointed Hilarion of Kiev as metropolitan bishop, the first Slavic clergyman in that role. He also captured Tartu, Estonia in 1030, defeated the Pechenegs decisively in 1036, and forged alliances through the marriages of his children to royal families across Europe.
Yaroslav the Wise arranged three confirmed royal marriages for his daughters: Elisiv married Harald Hardrada; Anastasia married the future Andrew I of Hungary; and Anne of Kiev married Henry I of France, later serving as regent of France during their son's minority. A possible fourth daughter, Agatha, may have married Edward the Exile of England and was the mother of Edgar the Aetheling and Saint Margaret of Scotland.
Yaroslav the Wise was entombed in a white marble sarcophagus in Saint Sophia's Cathedral in Kiev. When the sarcophagus was opened in 2009, it contained only an unidentified female skeleton. Investigators concluded that his remains had been deliberately hidden before the German occupation of Ukraine in the Second World War and were either lost or transported to the United States, where religious artifacts were sent to protect them.
Adam of Bremen first named Yaroslav as a saint in 1075, but formal canonization came much later. On the 9th of March 2004, the Ukrainian Orthodox Church (Moscow Patriarchate) added him to its calendar of saints on the 950th anniversary of his death. On the 3rd of February 2016, the Council of Bishops of the Russian Orthodox Church established church-wide veneration of him as "Saint Blessed Knyaz Yaroslav the Wise".
Four towns across four countries carry Yaroslav's name, three of which he founded: Yaroslavl in present-day Russia, Jaroslaw in Poland, Yuryev (now Bila Tserkva) in Ukraine, and Yuryev built on the site of captured Tarbatu, now known as Tartu in Estonia. The Yaroslav Mudryi National Law University in Kharkiv, Ukraine, also bears his name.