Rukia: I will kindly explain with illustrations so even a brat like you can understand.
Shut up and listen.
Now,
in this world there are two types of spirits.
One is called plus and is the most common spirit.
You can say that the "ghosts" you usually see are these.
And the other type is
called "Hollows" and these attack living beings and dead beings alike and eat there souls.
These are what you call "Evil Spirits."

Do you have any questions so far?

Ichigo: Uhmm..
Can I start by asking why your drawings abnormally suck?

1. Death and the Strawberry, Death and the Strawberry, Bleach ~ Kubo Tite