裤子 (kùzi) means 'trousers' or 'pants.' It is one of the basic clothing vocabulary words in Chinese. The suffix 子 is a common noun suffix that does not carry independent meaning here.
今天太冷了,穿条厚裤子吧。
jīntiān tài lěng le, chuān tiáo hòu kùzi ba.
It's too cold today; put on a pair of thick pants.
妈妈给我买了一条新裤子。
māmā gěi wǒ mǎi le yī tiáo xīn kùzi.
Mom bought me a new pair of pants.
这条裤子有点长,需要改一下。
zhè tiáo kùzi yǒudiǎn cháng, xūyào gǎi yīxià.
These pants are a bit long and need to be altered.