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What does it mean when there's very long bar? I've encountered this many in novels etc. Also, can someone write the long bar correctly? For some reason there are spaces in my version (5 different parts) and there should be just 1 long part.
For example (I've seen longer ones, but here we have examples of a normal bar, and then bars that are 3 times that size). This is just so that you understand what I mean, unfortunately I don't have scans for the ones that are longer than that.
This "horizontal bar" is called ダッシュ and serves more or less the same purpose as an em dash in English — inserting additional information to a sentence without ending the sentence or separating it completely from the sentence in parentheses (see what I did there?).
It can be used in pairs — like this —, or simply once.
Unicode does have
U+2E3A TWO-EM DASH ⸺
U+2E3B THREE-EM DASH ⸻
but I don't know if they are used by Japanese publishers, since they often have to typeset vertical text, as in your example. One also often sees "——" instead, especially on the internet. Depending on the font there will be small spaces, but everyone knows what is meant.
There is an obvious reason for using a longer dash (or several shorter ones): a single dash looks too similar to the 長音符
U+30FC KATAKANA-HIRAGANA PROLONGED SOUND MARK ー
