The Biblical Hebrew Calendar, also known as the Jewish calendar, is a lunar-solar system with deep historical and religious significance. It consists of 12 months, alternating between 29 and 30 days, and occasionally includes an intercalary month to align with the solar year. This calendar determines Jewish holidays, including Rosh Hashanah and Passover, based on its unique calculations, preserving ancient traditions and connecting the Jewish community to its religious roots.