USAGE NOTE 用法说明: clothes, piece of clothing, and 和 garment
Clothes is a plural noun and cannot be used in the singular. Use it to talk generally about the things that people wear. clothes 是复数名词，不能用作单数，它用来泛指人们一般所穿的衣服:
It might be cold, so bring some warm clothes. 天可能会冷，所以带一些保暖的衣服。
I don't have any formal clothes. 我没有正式场合穿的衣服。
If you are talking about something such as a shirt, skirt etc, say a piece of clothing or, more formally, a garment. 如果指衬衫、短裙之类的衣服，用 a piece of clothing 或较为正式的 garment 一词:
Customers may take two pieces of clothing/garments into the fitting room. 顾客可拿两件衣服进试衣室。
Usually, however, you can use a more exact word for a piece of clothing. 不过通常可以用更为精确的词来指“一件衣服”:
Someone spilled red wine all over my dress. 有人把红酒溅在我的连衣裙上，弄得满身都是。
That's a nice shirt. 那是件漂亮的衬衫。