In short, the One Power is kinda like the Force in Star Wars. It exists all around you, and only some can use it. The One Power is what powers the Wheel of Time, so it is very strong. The use of the One Power is called channeling. Very few people can learn to channel, even fewer are born with the ability. The Wheel of Time deals a lot with the One Power and channeling and stuff, so it is VERY important to understand.
People who can channel are refered to as Aes Sedai.
Some people, depending on their strength, can channel more than others.
The One Power is divided into five elements, Fire, Water, Air, Earth, and Spirit.
All Aes Sedai are stronger in one of these than the others. Some, if very strong,
are strong in two or three, but this is very rare.
In the Age of Legends, it was known that male Aes Sedai were stronger in Earth
and Fire, while females were stronger in Air and Water.
Many people think that Earth and Fire are much more powerful, so the females
keyed a syaing something like this