Complex sentence: Ivan Ivanovich (Ива́н Иванович) (28 March 1554--19 November 1581) of the House of Rurik, was Tsarevich-the heir apparent-of the Tsardom of Russia, being the second son of Ivan the Terrible by his first wife Anastasia Romanovna.
Split into simpler sentences: Ivan Ivanovich (Ива́н Иванович) (28 March 1554--19 November 1581) of the House of Rurik, was Tsarevich (heir apparent) of the Russia. Ivan was the second son of Ivan the Terrible by his first wife Anastasia Romanovna.