The blessings of Maa Baglamukhi make a divine protective defend in the shape of the aura all over somebody thus preserving him/her from malefic energies in the shape of black magic spells or evil eye. Another etymology suggests that valga indicates "to paralyze" and symbolizes the power of stambhana, "paralysis" https://www.youtube.com/shorts/5VeSyP9JRw0