周五 (zhōuwǔ) means "Friday" and follows the Chinese system of naming weekdays by number, where 周 means "week" and 五 means "five" (the fifth day). It is interchangeable with 星期五 in everyday use. Days of the week are commonly used with prepositions like 从 (from) and 到 (to).
周五下班后我们去吃火锅吧。
Zhōuwǔ xiàbān hòu wǒmen qù chī huǒguō ba.
Let's go eat hot pot after work on Friday.
这份报告周五之前必须交。
Zhè fèn bàogào zhōuwǔ zhīqián bìxū jiāo.
This report must be submitted before Friday.
他每个周五都会去健身房。
Tā měi ge zhōuwǔ dōu huì qù jiànshēnfáng.
He goes to the gym every Friday.