The 12th house is the last house of your astrological birth chart, and the end of a planet's journey through the entire zodiac and your chart. After that, the planet returns to your 1st house, starting the cycle through your chart all over again.
The 12th house is a key player in your connection to spirituality. While the 9th house is associated with more tangible concepts of religion, it's your 12th house that shapes your deep, inner, personal approach to what you think spirituality is. The 12th house is also a place of escapism, privacy, and subconscious thoughts, allowing healthy time for rejuvenation, integration and contemplation before, as mentioned before, beginning the cycle all over again.