The Impersonal se (General Truths)
When talking about local customs or general rules, you often need to say what "people", "you" (in general), or "one" does. In Portuguese, you express this by attaching the pronoun se to the third-person singular form of the verb.
The Passive se (Plural Agreement)
If the general action is happening to a specific noun, the sentence acts like the passive voice (e.g., "dinners are served" instead of "one serves dinners").
Crucially, the verb must agree with the noun being acted upon. If the noun is singular, the verb is singular. If the noun is plural, the verb must be in the third-person plural form.
When se Moves Before the Verb
By default, se attaches to the end of the verb with a hyphen. However, certain "trigger" words pull the pronoun directly in front of the verb, dropping the hyphen entirely.
The most common trigger is the negative word não.
Other triggers include question words and relative pronouns, such as onde (where) or que (that), which also force the pronoun to jump in front of the verb.
