Learn Hardcore Portuguese (Brazil): É importante que você guarde os documentos na pasta azul. - It is important that you keep the documents in the blue folder.

Breakdown of É importante que você guarde os documentos na pasta azul.

Why is it que você guarde and not que você guarda?

Because after É importante que..., Portuguese normally uses the subjunctive.

The subjunctive is used here because the sentence expresses importance, necessity, recommendation, or emotion, not a simple statement of fact.

So:

É importante que você guarde os documentos... = It is important that you keep/store the documents...
Using guarda here would sound ungrammatical in standard Portuguese.

This is a very common pattern:

What exactly does que mean here?

Here que means that.

It links the first part of the sentence to the second:

É importante = It is important
que você guarde os documentos na pasta azul = that you keep the documents in the blue folder

So the whole structure is:

This is one of the most common ways Portuguese introduces a subordinate clause after expressions like:

Why is você used? Could it be omitted?