What does `incoming link count` in discourse database mean?

I was hoping that incoming link count for a post in discourse database means no. of times external websites have mentioned that post in their content… But the numbers that I have are too high to believe that.
Could someone please explain what does incoming link count mean?

I believe it is the number of incoming links from the forum itself, that is, the number of other posts that have linked to that post.

There is no rational way to determine how many times external websites have linked to a place without crawling the entire web, like Google.