不没有用 is a common phrase in Chinese that is used to describe something that is useless or ineffective. It is made up of two characters: 不 (bù) and 没有 (méiyǒu).

The character 不 (bù) is a negative adverb that is used to indicate that something is not the case or does not exist. For example:

这个方法不好。 (Zhège fāngfǎ bù hǎo. This method is not good.)

The character 没有 (méiyǒu) is a negative verb that is used to indicate that something does not exist or is not present. For example:

我没有钱。 (Wǒ méiyǒu qián. I don't have any money.)

Together, 不没有 (bù méiyǒu) is used to describe something that is useless or ineffective. For example:

这个东西不没有用。 (Zhège dōngxi bù méiyǒu yòng. This thing is useless.)

In English, we might say something is "useless" or "ineffective" to convey the same meaning. For example:

This method is useless.

I don't have any money.

This thing is ineffective.