Breakdown of Pour la sécurité, il faut mettre un casque.
pour
for
il
it (impersonal subject)
falloir
to be necessary / must (impersonal)
la sécurité
the safety
Questions & Answers about Pour la sécurité, il faut mettre un casque.
Why does the translation say "you must" if the French says il faut?
Il faut is a special expression meaning "it is necessary." The il doesn't refer to "he" or any specific person here. Because English sounds strange if we say "it is necessary to put on a helmet," we usually translate it as a general "you must" or "one must."
Why is mettre left in its infinitive (dictionary) form here?
After il faut, the action verb that follows is always in the infinitive. That's why we use mettre (to put on) rather than a conjugated form. The rule for this structure is always il faut + infinitive.
Does mettre mean "to put" or "to put on"?
Why is it la sécurité and not just sécurité?
French loves its articles! Unlike English, which often drops the "the" for general concepts (like "safety"), French requires a definite article (le, la, l', or les) for them. So, "for safety" becomes pour la sécurité (literally "for the safety").