Learn French: Les couteaux sont dangereux, ne vous blessez pas ! - Knives are dangerous, do not hurt yourselves!

In an affirmative command (telling someone to do something), the reflexive pronoun goes after the verb with a hyphen, like blessez-vous. But in a negative command (telling someone NOT to do something, which is the focus of this lesson), the pronoun moves back in front of the verb. It gets sandwiched between ne and the verb, making it ne vous blessez pas.

Why does couteaux end in an x instead of an s?

In French, nouns ending in -eau, -au, or -eu usually take an -x instead of an -s to form the plural. Since the singular word for knife is couteau, the plural is couteaux.

Shouldn't dangereux have a plural ending to match les couteaux?

It is already plural! Adjectives that end in -s or -x in their masculine singular form do not change when they become masculine plural. Since couteau is masculine, dangereux is spelled exactly the same way here as it would be for a single knife (un couteau dangereux).

Could ne vous blessez pas mean 'do not hurt yourself' to just one person?

Yes! Because the pronoun vous is used both for groups (plural 'you') and for formal situations (respectful singular 'you'), this warning could be addressed to a group of people or to a single person you are being polite to. The sentence looks identical either way.