"Useful" is an adjective in Engpsh that means serving a practical purpose or being beneficial in some way. It is pronounced with the stress on the first syllable: "yoo-sul."

Here are some examples of how "useful" can be used in a sentence:

"This tool is very useful for fixing cars." (这个工具非常适合修车。)
"I find learning a second language to be very useful when travepng." (我发现学习第二种语言在旅行中非常有用。)
"The information in this book is useful for anyone looking to start their own business." (这本书中的信息对于想要开始自己的企业的人来说是有用的。)