In addition to Facebook announcing yesterday at fMC that users will start seeing ads with the mobile app, another tool that Facebook will be offering to businesses looking to expand their presence on the site is Facebook Insights. In a nutshell, it’s Google Analytics for your brand’s Facebook Page, but here’s a more detailed look at what the service looks like.

Basically, Insights allows all Page administrators and developers access to the Page’s metrics so they can see how their posts are performing across the site. Admins will be able to see how many Facebook users a post reaches, how many users it engages, and how many people then begin a discussion about it.

The information at the top of the page displays the main figures that businesses will want to pay attention to, but most telling is the Friends of Fans number. As you can infer from the name of this figure, it’s the total amount of people who are friends with the Page’s fans yet haven’t actually committed to being a fan themselves. Knowing how many prospective Page fans are literally one degree away from becoming actual Page fans will likely play heavily into how businesses develop strategies to attract those Facebookers.

The People Talking About This keeps track of the amount of Facebookers who are talking about the business among their friends. This doesn’t mean that any and all name-droppings of a brand automatically gets beamed back to a business’ Page. Information included in these metrics only includes Likes, Likes or comments on a post, responses to polls or events, mentions and photo tags, or anyone who check in via a business page. This means when you reply to a friend’s post and say, “Incredibly, you’re stupider than a bag of Doritos,” that kind of statement wouldn’t get included in Doritos’ official data. Well, it wouldn’t unless you actually tagged Doritos so as to link back to their Page.

Another peculiar metric to look at is the difference between Reach and Engaged Users. Reach merely refers to the amount of unique people that have seen a post from a business’ Page, whereas Engaged Users are people who have actually clicked something within the post (links, I imagine, as miscellaneous clicks on random text won’t be collected as data).

Insights also provides Page admins the demographic info of its fans. This metric is pretty self-explanatory, but here’s what it will look like in Insights:

It’s worth noting that, as far as the viewable data goes for Page audiences, businesses will only be able to use Insights for posts published after July 19th, 2011. Still, there’s a ton of data for advertising statisticians to play around with here that wil undoubtedly be valued by businesses as they seek to how best to market products to Facebook users.