Soul points are points for your soul, You start out with 10 and you lose 2 at death. If you lose all your soul points, You'll lose all your items. You will get 1 extra soul point each minecraft day at sun rise. 

"As the soul rises, you feel a bit safer..." you'll see in chat so you know when you get an extra soul point. It will warn you when you have low soul points. Make sure you keep your soul points safe!

Theres one way to increase your soulpoints, simply donate to VIP, and you can have a maximum of 15 soul points, instead of 10.