Passiva in Portuguese grammar refers to the passive voice, a construction in which the subject of the sentence receives the action of the verb, rather than performing it. The passive voice is formed by combining a form of the verb ser (to be) with the past participle of a verb. In Portuguese, there are two types of passive constructions: the normal passive structure (with an explicit agent) and the impersonal passive structure (without an explicit agent). The choice between these two constructions depends on whether the speaker wants to emphasize the agent or the action itself. Learning how to form and use passiva is an essential part of studying Portuguese grammar, as it allows for greater flexibility and precision in expressing ideas.