Although there are links to what those acronyms stand for, some context ought to be given to explain the manner in which they're used.
HB = Hot Babe, Hot Broad, etc. Take your pick of B word. Followed by a number such as HB9 it would be referring to her perceived attractiveness on a scale of 1-10. The term is overused though, and is frequently referring to any woman you meet that you'd bang, regardless of how "hot" they are.
AW = Attention (W)hore. You'll notice that a lot of posters will use this term to describe women who are more blatant or aggressive in their attention-seeking behaviors, even though all women seek male attention to a degree to validate their sexual value.
AFC = Average Frustrated Chump. Refers to the prototypical male who has trouble getting laid and effectively interacting with women. An R in front of it means Recovering AFC. Around this forum the term is also used as an adjective to describe other facets of an AFC's life paradigm, characterized by an un-confident lack of control over their beliefs, emotions, and actions. Conversely, the acronym DJ (Don Juan) is used to describe the opposite dynamic - a confident man in control of the reality he creates for himself.
LJBF = "Let's Just Be Friends". It's when women reject a male with this rationale to opt out of any sort of sexual relationship while retaining the attention the male gives and/or keeping him around for additional self-serving purposes.
"The Matrix" = An analogy to the virtual world and manipulation of human minds in the film The Matrix. It references the fact that the far majority of Western society, along with mainstream media, promotes and assumes feminized AFC ideals.
These are the main ones that you'll see.