TanzanianGod said:
There are endless different frequencies of energy. Every being in the universe has one. This is important mainly for things like astral communication, such as what we are doing when we communicate with the Gods.
A sigil is a very specific energy frequency turned into an image. Through the sigils of our Gods, we can tune into their exact unique frequency and, with enough practice, communicate with them accurately. Meditating on such a sigil lets you feel their energy and connect to them through it. For example for people who know who their GD is, they can meditate on his/her sigil and breathe in the energies daily to establish a strong connection. That would then help with communication and receiving signs and advice more effectively.
The enemy has worked for thousands of years to stop this from happening. On the JoS it is mentioned that the enemy had "bound" our Gods, and that Maxine freed them again. This "binding" was done in a way of erecting a psychic barrier around the Earth that jams the Gods' unique "radio signal" so they cant properly communicate with us and guide us (the circle that was drawn around their sigils by the enemy). Of course, this didn't stop them in the end as they are far more powerful, but it was likely a bit of a hindrance. I wrote more about this
here and
here if you are curious.
Anyone can have a sigil, but you would need the in-depth knowledge on how to make one if you wanted to truly create a sigil for yourself that is on the level of accuracy as the ones of our Gods. I haven't seen any knowledge of that level around yet, so it's likely not possible with the limited info we have at the moment.
It would be useful mainly if you wanted to allow some people to contact you psychically and/or to learn from you more effectively. These things are also possible without a sigil, but having a sigil makes focusing on the specific energy frequency much easier. Without a sigil, a very strong energetic connection would be needed to accomplish the same thing.