Translation:Please do not wait in line in front of the convenience store.
If you check out the link, it says that the correct usage (which many average Japanese people don't actually know) is that when it is used with a verb, it is written in kana, and when it is used with a noun as an object, it should be written with kanji. That is the correct grammatical usage, even if people do not use it correctly.
In Computer Science, a "queue" is a "first in, firs t out" (FIFO) structure, the opposite of a "stack" (LIFO).
Speaking of which..
PISTOL - A Forth-like Portably Implemented STack Oriented Language, Dr Dobbs Feb83, 12; Jul84, 102 - Bergmann, E.E. (1983)
ForthもDr. Dobb's Journal (1976-2014)も懐かしい。
Here in England no one says convenience store either. Corner shop, newsagents, or very often the name particularly "Co-op", or yeah probably most often just "shop" and "the shop".
But then again, having been to コンビニ in Japan, their コンビニ are so much more "convenient" than our shops that I'd want to refer to them as convenience stores anyway! :P
In everyday speech, no, I don't many of us in England say 'convenience store'. But the term is definitely used here.
Floor space is very expensive in Tokyo I would assume some stores being smaller.
But if that's wrong, I have at least seen people Form lines 10 meters or so long. Because they waited for a video game release.
I would assume for young people mangas, anime or video games is one motivation for learning Japanese.
I guess it's a funny story to see that sign after having wait in such a line yourself
There is a conditional word ならば that means "if", but in this sentence ならば by itself doesn't have any meaning. It's part of the conjugated verb 並ばないで (narabanaide, don't line up).
並びます (narabimasu) - (someone) lines up
並びません (narabimasen) - (someone) doesn't line up
並ばないで (narabanaide) - don't line up (a command)