I see that, at the bottom of this lesson, there's a note that says what "pluscamperfecto" refers to. It's a very simple explanation -- to talk about something that had happened.
It would be SO helpful to have these short explanations of what a given grammar term means at the TOP of the lesson, just below the term for the lesson. I look at all these grammar terms and my eyes cross. I have no idea what they mean and I start to feel like there is no way I can learn Spanish because I'm so lost in all these terms. Taking the time to learn grammar terms seems like a tedious distraction from just learning to speak Spanish: a roadblock.
It's not uncommon for people in the US to have never learned grammar, so on behalf of myself, and all the mediocre public school graduates, I implore you: move the explanation for what a grammar term is to the top of the lesson. It's such a simple change and will make learning so much more accessible and these lessons so much more meaningful.