First you have to understand chakras. There are seven key Chakras in our bodies and the pineal gland is the 6th one whish is also known as “The 3rd Eye”. The pineal gland activation will help the 6th Chakra reach its potential, which includes clairvoyance, psychic abilities, imagination, and dreaming.
The Pineal Gland like a link between the physical world and the spiritual world. its like your spiritual eye and its opens the ability to see the astral realm (Spirit Realm)
Other benefits of pineal gland activation include telepathy and a greater level of perceptiveness that can go beyond this three dimensional world.
There’s a lot more to be said but you should just google it and research more for yourself .
Videos that can help here :