A bar goes straight across the disk of a galaxy, rather like a long thin piece of pancake across a plate. Therefore you won't see an actual bar in an edge-on. What you're seeing there is a very bright area of disk; you're seeing that on edge too, and therefore you're looking through many light-years of stars, so it does look bright - and quite straight.
If an edge-on spiral has a bar, what you'd probably see is a boxy bulge.
We ask about bars because they're a very common feature of spiral galaxies, and we don't know for sure how they form. You'd think that in a rotating disk, there shouldn't be a straight bit; you'd think that would collapse into the spiral. But that doesn't appear to happen - in fact, the reverse (red spirals, and spirals that appear older, seem to have more and/or large bars than young or blue spirals). So we ask because we'd like to know why they exist. This old Object of the Day
addresses your question. It was inspired by a lecture given by an astronomer who's not part of the Galaxy Zoo team, and I don't know how closely related the work is - so we might end up finding different things to him - but hopefully at least it will be interesting to you