We often denote danger by red letters.是什么意思？

We often denote danger by red letters.

我们常常用红字表示危险.

we

pron. 我们，咱们，笔者，本人，朕，人们；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

often

adv. 常常，经常，时常，再三；

例句
Genetic abnormalities are more often associated with faults in paternal DNA than in maternal DNA.
相对于母本DNA,基因畸变往往更多地与父本DNA上的缺陷相关。

denote

vt. 指代，预示，代表，意思是；

例句
Red eyes denote strain and fatigue...
眼睛充血表明压力过大、身心疲惫。

danger

n. 危险，危险物，威胁；

例句
Many schools were in danger of closing because the children were bused out to other neighborhoods.
很多学校面临倒闭的危险，因为学生被校车送到其他社区就读了。

by

prep. 在…旁边，表示方式，由于，经过；adv. 经过，表示保留或保存时用，短暂拜访；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

red

adj. 红色的，（脸）涨红的，烧红的，红头发的；n. 红色，红衣服，红颜料，红葡萄酒；

例句
From her wardrobe Laura took her latest acquisition, a bright red dress.
劳拉从衣柜里拿出了她最近的购物战果，一件鲜红色连衣裙。

letters

n. <正>文学（作品），信( letter的名词复数 )，函件，字母，（缝制在运动服上的）校运动队字母标志（美式英语）；

例句
...a bundle of letters which had arrived for me in my absence...
我不在期间寄给我的一大堆信件