Let's do it fast. In this world there's a magic system based on what people from past Greek and Rome thought on how everything is created. they thought that everything in this world was made from the four elements- water, fire, earth and air (even though, fire is energy). They thought that everything was made out of certain percentage of this four elements. For example, clouds- they were made of 70% air and 30% water. For something more complicated, humans- their bodies were solid so 55% earth, and the had blood 35% water, dut they were warm 5% fire and there was a fifth element called the ether (no, not the mode from minecraft) which was supposed to be space, life, darkness, emotions and all the other shit that wasn't tangible and they didn't know were to put is, some people used air for this but I'm using ether, so the humans contained 5% ether for life.
Now that you understand the basics. in this worlds magic system you can use all types of magical abilities by combining different amounts of the elements into their power. That means that everybody starts with the same skills, but it's only if you know how to use them is when you get their full potential. The smarter you are with your elements, the more powerful you can get, the possibilities are limitless. People are able to use two types of magic but it's super complicated, and the ones who are able to use two types mostly use only basic elements. Like I said, the possibilities are endless, the only limit is the user, so there could be one user of light magic who can only make his body shine while another use can turn himself into light and move super fast.
But there's another factor for using magic, your mana, aka, your life force. I know, I know. You heard this shit a million times already, but I'm not here to reinvent the weal, I'm just a beginner writer. So even though it's super similar to Chakra from Naruto and endless power systems, mana isn't only the amount of power you have, it's also your life force. Everyone is free to use some mana, a bit more then others, but when you finish your renewable mana pool, if you want to use more you need to sacrifice some of your life force and it could cause permanent damage. Mana isn't directly correlated to the power of your magic, it's more your stamina.
People who want more mana, most of the time use spirits- the second power system in this world. The spirits is more like will power but every spirit as a life of her own. Spirits can remain in a solid state on earth, so the most common way for a spirit to exist is by possessing an item. Humans and spirits can form a connection, by contract and sometimes possessions, the human most of the times bonds to the item of the spirit, but of rare actions a spirit can be connected directly to a human. Spirits are full of mana and also their own magical abilities, the strongest people are the one who work in bond with their spirits powers, and not only using the spirit as a mana battery. There are two types of spirits, one is the normal one who is made out of will power, and the other one is demons. Demons are much more ancient then normal spirits and a lot of the times more powerful and hard to obtain. If a human uses an item for a long time, his will power can transfer into the item and create a new spirit.
So that's all I have to say and explain