1, ulla's explanation: this is a modal particle to express cheers. Used in extremely excited and celebratory occasions. In some films of the Great Patriotic War of the Soviet Union, when the battle was won or Stalin appeared, the soldiers made an earth-shattering "Hula" sound. So it is similar to the Chinese word "Long live". So it is generally translated as "Long live", and of course it can also be translated as "Oh" sometimes.
2. Wula in Russian is ура (pronounced as "Wula"), but "Wula" is associated with words such as "victory" and "military achievements" on more occasions. You can hear the endless "hula-hula" sound of crazy Russian fans after winning the game on the court. The most inspiring thing should be that after the Victory Day military parade speech, Putin never forgot to lead the soldiers of the three armed forces to shout "Ula" throughout the Red Square, which greatly boosted morale.