Since I like your picture so damn much, let me explain it to you. (+1 internet for you, sir!)

You probably have the "Generate Bitcoins" option enabled under "Settings".
This will cause Bitcoin to use your CPU to hash.
Once it hashed what it was looking for? You generated a block!
If the outcome of the hash is lower than or equal to "the target", the data that was hashed is a block. ^{Not sure about what exactly is the block, but I'm sure about the other stuff!}

So, your CPU is hashing data to generate blocks, and blocks are Bitcoins!


More information here:
http://www.bitcoin.org/wiki/doku.php?id=hash
http://www.bitcoin.org/wiki/doku.php?id=block
http://www.bitcoin.org/wiki/doku.php?id=target

Also: Sorry for letting you hang there, I had the tab open and everything typed out, I just never clicked "post!".