bar = a substance that has been made into a solid rectangular shape条状物。如a bar of soap一块肥皂；a chocolate bar一条巧克力棒。
bar的意思很多，作为名词，基本意“酒吧；酒吧的吧台”。
除了注意单词意思外，对于短语引用也要注意behind bars，= in prison“在监狱里”。

【例句】
There weren't any free tables, so I sat at the bar.
没有空桌子了，我只好坐在吧台旁。

We knew that you could see bars drop on the phone when you hold it in a certain way, it's a fact, phones aren't perfect.
你可能会发现，当以某种方式握住手机时，信号格会下降，这是事实，手机并不完美。