Complex sentence: Jisoo entered YG Entertainment as a trainee in July 2011, and she was first introduced to the public on May 4,2012, when a black-and-white photo of Jisoo was released without identifying her name.
Split into simpler sentences: Jisoo entered YG Entertainment as a trainee in July 2011. On May 4,2012, a black-and-white photo of Jisoo was released without identifying her name.