Confusion: First words and [first_post_X_words]

Ok, in quite a few SEO articles for vB, people mention first words. What are they? Where can I find them?

1 other question, vBSEO has this option for RR's:
[first_post_X_words]

How do I get that without using vBSEO? Such as [forum_title], vBulletin's way to get that is $foruminfo[title]. I figured there is something similar for [first_post_X_words].

I'm asking this b/c I was trying to set up my meta description to have the first post x words...I put an RR in my meta tags and it gave me xhtml errors. Why? B/c I have the Google Adsense feature turned on and I guess it's set to have the commented ad section to wrap around RR's....? IDK, but that's what happened so I'm trying to find an alternative now.

Please enlighten me, this isn't the first time I asked about first words...and I've not gotten an answer yet. :(

Hello,

vBSEO extracts specified number of words from the first message on the page, so it's not available directly as vBulletin template variable. You can insert <!--VBSEO_RR_X_NOHTML--> in meta tags to avoid html validation errors.

Great, thanks!

Any information about first words...? People talk about them...still don't know what they are.

You cannot insert them without vBSEO's Relevant Replacement feature.

Sorry, I want to make sure we are on the same page. T2D wrote about this before vBSEO I believe and he mentioned wrapping "firstwords" in h2 tags. You can find what I"m talking about in this post here:
For better Search engine rankings

Point number 9. If firstwords pertains to the vBSEO feature, then I'm good....I've just seen that posted a few times but no one says where to put the h tags at... :S

I see what you mean, I can't say exactly if that post refers to the same thing as [first_post_X_words].

Ok, thanks for your help once again Oleg. Much appreciated.