nonnel was kinda right too though cus I was actually asking about what that image was talking about
also what does "attack on titan" even mean anyway. the human city thing is not called "titan" so, what
Shingeki is just a nickname for the protagonists. It doesn't translate to anything fitting and I think it may be ironic.
As far as the title goes, most Japanese nouns don't have plurals; you can think of it as "Attack on Titans" if you'd like. Though that's a bit overly literal. Story-wise, the original name is actually fitting - though knowing why is a spoiler.