Complex sentence: Zejnullahu played in his youth career for SV Tasmania Gropiusstadt, FC Hertha 03 Zehlendorf and Union Berlin, which he joined in 2012.
Split into simpler sentences: Zejnullahu played in his youth career for SV Tasmania Gropiusstadt, FC Hertha 03 Zehlendorf and 1. FC Union Berlin, which he joined in 2012.