The users of this website have accumulated quite a few travel logs, or travel diaries, which provide personal accounts of their stay in Latin America or other Spanish speaking travel destinations.
First we need to know what we mean when we say a "passive" sentence.
"Passive" sentences can be understood best by contrasting them with "active" sentences. They can express the same idea, but in a different form. Let's take a look at the following two sentences:
John broke the window.
The window was broken by John.
In the first sentence, John is the subject. He is the one who does the breaking, the action which is expressed by the verb.
In the second sentence, the window is the subject, but the window doesn't do the breaking.