Hi, Im rather new here and I was wondering how one would get essence? I can see it can be used to generate pets but I couldn't find anything explaining how to obtain it. Is it bought or earned in some way?

you sometimes get them when fighting the wild sylestis but I have not got any yet you can also buy them from others

There are several ways you can get essences:
1)Your best bet is to buy them either off the broker or with diamonds.
2)Technical you can get them fighting and from doing missions, but they are insanely rare and I have never received one that way.
3)You can also get them from nurturing, but it is also very rare. I have received a few that way, but not very many.
4)You can get them playing Jinxie's Jamboree. I don't play the game, so I don't know the rarity first hand, but I've heard that it is also very rare.

What Faeyla said, essentially.

I have managed to get...probably 5 essences in my time playing, which is probably about a quarter of the age my account actually is. It's truly rare, but if you don't focus on getting them, you'll notice one day that you have one sitting in your inventory and can use them!