The about.com page can explain it better than any of us, I think.
As for reflexive pronoun, that means a phrase that uses "sich", for example: "Machen Sie sich (r.p.) über mich (a.c.) lustig?" - "Are you making fun of me?" (literally 'do you make yourself happy over me/at my expense')
r.p. = reflexive pronoun a.c. = accusative case