Complex sentence: Soon after, he began to study acting at the Prague Conservatory, from which he was expelled in the fourth year for a high amount of absences, which originated when Hádek began actively pursue acting while still studying.
Split into simpler sentences: Soon after, he began to study acting at the Prague Conservatory, from which he was expelled in the fourth year. The reason for the leaving school was high amount of absences, which originated when Hádek began actively pursue acting while still studying.