This is an activation of the 'secret chakra' known as the Hrit Chakra. It is also known as Hridaya or Surya (Solar) chakra. It is located approximately 2 finger widths beneath the physical heart and when awakened, it helps embody your higher self/inner teacher and open you to unconditional love.
Some associate it with the sacred heart in depictions of Jesus and in some some sufi schools, latifa-e-qalb (subtle center of heart/mind) because it is where the atma (essence/breath/soul) meets the Paramatma (supreme Self). In some sufi schools, it is associated with the first man Adam or in kabbalah, the primodial/supreme man (Adam Kadmon).
With time, this will open a corresponding feminine chakra called chandra (lunar) chakra on the right side which in sufisim is called latifa-e-ruh (subtle center of the spirit).
Here is some more information about this chakra: https://medium.com/@hannatantra/the-secret-chakra-hrit-f6cccf1e3e8a