Complex sentence: On the mount there is a very holy site to many Jews, especially Orthodox Jews, because it houses the tomb of Rabbi Simeon bar Yochai, which on Lag B'Omer many Orthodox Jews come to celebrate the anniversary of his death.
Split into simpler sentences: On the mount there is a very holy site to many Jews, especially Orthodox Jews, because it houses the tomb of Rabbi Simeon bar Yochai. On Lag B'Omer many Orthodox Jews come there to celebrate the anniversary of his death.