Learn Italian: È importante rispettare le regole. - It is important to respect the rules.

In Italian, subject pronouns like "it" are almost always left out. To say "It is [adjective]", you simply start with the verb è (is). For example, È importante (It is important) or È facile (It is easy).

This lesson is about dovere (must / to have to). Why doesn't this sentence use it?

Saying È importante rispettare le regole (It is important to respect the rules) is just another way to express an obligation, which ties directly into this lesson! It functions very similarly to Dobbiamo rispettare le regole (We must respect the rules). Notice that both structures are followed directly by an infinitive verb.

Why do we use the full dictionary form rispettare (to respect) here instead of conjugating it?

Just like in English, when you make a general statement with È importante (It is important), you follow it directly with an infinitive (a verb in its original, unconjugated form ending in -are, -ere, or -ire). Because it's a general statement not tied to a specific person like "I" or "you", the verb doesn't need to change.

Does importante change depending on whether what you're talking about is masculine or feminine?