Complex sentence: On 8 January 2014, he signed a 4-year deal with Schalke 04 and he will join the club in summer upon completion of the 2013-14 Bundesliga season.
Split into simpler sentences: On 8 January 2014, he signed a 4-year deal with Schalke 04. He will join the club in summer upon completion of the 2013-14 Bundesliga season.