Blog Roll and Meta

Hi!
It may be a silly question but I just need an answer.
I would like to know if other people can see Blog Roll and Meta catergories? I tried to log out from my wordpress blog to see if I can see those (and I could) I dont’ know how can I remove “Log In” link, “wordpress” under Meta catergory. I removed everything from Blog Roll (but the category is still there. Have I done something wrong?
I just need to know how can I have simply my blog without any other things on it (like these two links: Blog Roll and Meta)…?
What does Blog Roll mean really? and what Meta means?
Thank you