Learn Italian: È importante che voi pensiate alla vostra sicurezza. - It is important that you think about your safety.

The sentence starts with È importante che (It is important that). This is an impersonal expression that states an opinion, value, or necessity, which acts as a strict trigger for the subjunctive mood. Because of this trigger, the normal indicative verb pensate must change to the subjunctive pensiate.

Why does the sentence use alla for 'about'? Wouldn't we use di?

The verb pensare requires the preposition a when it means 'to think about' in the sense of directing your attention or care toward something. You mostly use pensare di when asking for an opinion, like 'what do you think of this?'. Because the preposition a is followed by la vostra sicurezza, it merges with la to become alla.

Why is there a definite article (la, hidden inside alla) before vostra?

Unlike English, Italian requires a definite article before a possessive adjective in almost all cases. So, 'your safety' translates to la vostra sicurezza. The only major exception to this rule is for singular family members (like vostra madre), but for a regular noun like sicurezza, the article is mandatory.

Since pensiate is uniquely the voi form, is the word voi actually required here?