What exactly is the passive voice ?

The passive voice or la voz pasiva is commonly used in spanish 

The Passive Voice is used when it is stated that an action happens without stating who exactly is carrying out the action. In English we often translate this as you or more commonly as they e.g you must or they must.   Using the “queen’s” English this would be translated as “one” e.g. one must.

In Spanish this tense is formed by using the pronoun SE + the 3rd person singular or the third person plural of the verb.  

Se habla inglés en Inglaterra.  They speak English in England.

Singular used as only English is spoken.

Se hablan inglés y francés en Canadá. They speak English and French in Canada.

Plural is used as both English and French are spoken.

Se vende pan en la panaderia. They sell bread in the bakers.

Singular is used as only one pan.

Se venden hamburguesas en McDonalds.  They sell hamburgers in McDonalds.

Plural is used as hamburguesas.

Se construye el edificio. They construct / build the building.

Singular is used as el edificio.

Se construyen los edificios.  They construct / build the buildings.

Plural is used as los edificios.