What exactly does a Prayer bonus do?

I understand that while wearing Monk's Robe (Top) and Monk's Robe (Bottom), you are given +11 prayer bonus in total.

My question is, what exactly does the prayer bonus do?

Does it mean you are given 110 extra Prayer points? Or does it mean your Prayer is 11% more effective than without the bonus?

 

Pray bonus makes your prayer drain slower

 

It makes your prayer last longer than it normally would.

Check this out:
http://runescape.wikia.com/wiki/Prayer#Prayer_bonus

 

Obvious I thought lol

 

When you use you'r prayer it drains obviously, but having the prayer bonus makes it drain X amount of percent slower than what it would without any bonuses.

 

So +11 from monk robes would be 11% slower?

 

Prayer drains slower.