PBN stands for Private Blog Network. It's a chain of niche related blogs owned by the same person that all link to each other some how. It's gotten harder to successfully run PBNs after the latest algorithm updates came out - but it still can be done. Here is some more info: https://en.wikipedia.org/wiki/Blog_network
Forum backlinks WILL in fact raise your rankings - I am doing a case study on that now. However, the keyword(s) you are targeting need to be super low competition. My advise? Use Ahrefs, Majestic or MOZ to figure out what backlinks your competition have - and build your SEO strategy from there.
Backlinks are possible through top high Pr directories, Top high Pr Bookmarking submission and even High Pr forums sites use them make your backlinks like Wikipedia
i think this is dropped or deleted domain, now he want to get visitors on his site through here, please stop replies to this guy
You can try to forum posting, blog commenting, infographic submission and Social media and post your website link and get back to organic traffic to your website.
An easy way to increase backlinks is by commenting on blogs and forums. Another thing you can do is link to other sites (as long as they are relevant and credible) on your site. These strategies might take a while to generate results, but they are easy ways to get backlinks. You can also buy backlinks from SEOclerks.
You said have a lot keywords and get high rank and not have a traffic, maybe the keyword it's not have a good searches and of course your site not have e good traffic. Maybe you can see your keyword using google keyword planner or semrush !