Breakdown of Pulisci la maschera prima di indossarla!
pulire
to clean
la
her/it (direct object)
prima di
before (doing something) / before (a noun / point in time)
indossare
to put on
Questions & Answers about Pulisci la maschera prima di indossarla!
Why do we use prima di followed by the infinitive indossarla?
Why is the word la attached to the end of indossarla?
Why is the verb pulisci instead of pulire?
The sentence gives a direct command to one person (the informal "you"), which requires the imperative form. For -ire verbs like pulire (to clean), the informal command uses the same ending as the normal present tense tu form. Because pulire is a verb that inserts -isc-, the correct form is pulisci (Clean!).