"Talking about this" What is it exactly?

When it says a number of people are "talking about this", what does it exactly mean?

What did they do for it to count as 1?

I know they probably shared it or something but I'm looking for an official or right answer from someone who exactly knows how it works.

Much appreciated.

According to me it means that how many people are sharing, commenting or liking your updates in recent..

Talking about this means a combination of likes and comments received for the set of updates posted on the fan page... what i am not sure of is Is it daily or weekly ?