This is the shiva beej mantra. Here the “HA” stands for shiv and “UM” means Sadashiv. To evoke the blessings of Lord Shiva, chant this mantra holding lord shiva in your mind and concentrating on him only. काल भैरव, भगवान ब्रह्मा के पास गए और उनके ऊपरी सिर को https://www.youtube.com/watch?v=0vLISs2kzMI