Why are there so many external links to the site pages?

Question

Search Engine Optimization

In Yandex webmaster such a picture . Why is this and what to do about it?

Answer 1

To begin with, look at what sites they lead from, perhaps on some large site there is simply a through link to your site.

Answer 2

Perhaps the site that links to you was hacked, it would be nice to write to its owner and inform about the links, maybe he will fix everything himself and the links will disappear.