Complex sentence: This is the so-called "saltus lunae" or "leap of the moon", and it is handled in the Julian calendar by reducing the length of the lunar month which begins on 1 July in the last year of the cycle to 29 days.
Split into simpler sentences: This is the so-called saltus lunae "(" leap of the moon). The Julian calendar handles it by reducing the length of the lunar month that begins on 1 July in the last year of the cycle to 29 days.