它们是五彩缤纷的用英文怎么说

"They are colorful" 是五彩缤纷的简单翻译。

来源：colorful是形容词，来源于英文color（颜色）和-ful（充满）后缀。

例句：

The sunset was so colorful, it looked pke a painting.
(夕阳颜色鲜艳，仿佛一幅画。)
The festival was a feast of color, with people dressed in bright clothes.
(节日五彩缤纷，人们穿着明亮的衣服。)