Es la calle en que trabajamos.

Because ser is often used to identify or define something: It is the street...

Here, the sentence is identifying which street we mean. It is not mainly talking about location in the sense of The street is located...

• Es la calle... = It is the street...
• Está en Madrid = It is in Madrid

So es is natural because the sentence is equating one thing with another: This = the street where we work.

Because calle is a feminine singular noun, so it takes the feminine singular definite article la.

• el libro
• la casa
• la calle

Spanish uses articles more often than English, so where English might say It is the street where we work, Spanish naturally says Es la calle...

Here en que means something like where or more literally in/on which.

So:

• la calle en que trabajamos = the street where we work
• more literally = the street on which we work

Spanish often uses a preposition plus que after a noun:

• la ciudad en que vivo = the city where I live
• la mesa en que comemos = the table at which we eat

In this sentence, en is there because with trabajar and calle, the idea is work on a street / in that place.

Yes. Es la calle donde trabajamos is very natural and probably more common in everyday speech.

You may also hear:

• Es la calle en la que trabajamos
• Es la calle donde trabajamos
• Es la calle en que trabajamos

All three are possible, but they feel a little different:

• donde = very common and natural for places
• en la que = very clear, slightly fuller
• en que = correct, but a bit more formal or literary in some contexts

For many learners, donde is the easiest everyday choice.

Because this que is a relative pronoun, not a question word.

Compare:

• la calle en que trabajamos = the street where we work → no accent
• ¿En qué calle trabajamos? = What street do we work on? → accent

Use qué with an accent in direct or indirect questions. Use que without an accent in relative clauses like this one.

Because Spanish normally keeps the preposition before the relative word.

In English, we can say:

• the street where we work
• the street that we work on
• the street we work on

But in Spanish, you cannot usually drop the preposition like English does. You need something like:

• la calle en que trabajamos
• la calle en la que trabajamos
• la calle donde trabajamos

So Spanish is more explicit here.

Trabajamos can be either:

• we work = present
• we worked = preterite

In this sentence, it is normally understood as the present: we work.

The context makes that clear. Without context, the form is ambiguous, but here the most natural meaning is present.

Because Spanish often places the main statement first and then adds the relative clause that describes the noun:

• Es = It is
• la calle = the street
• en que trabajamos = where we work

So the structure is:

Es + noun phrase + relative clause

This is very normal in Spanish. It works just like:

• Es la casa donde vivo
• Es el bar en el que nos vemos

It is standard Spanish, including in Spain, but it is not limited to Spain. Speakers in many places will understand and use it.

That said, in everyday conversation many speakers, including in Spain, may prefer donde or en la que with place nouns:

• la calle donde trabajamos
• la calle en la que trabajamos

So en que is correct and standard, but it may sound a little more formal or less conversational than donde in some situations.

Yes, absolutely.

• Es la calle en que trabajamos = It’s the street where we work
• Esta es la calle en que trabajamos = This is the street where we work

Adding esta makes the sentence more explicit, especially if you are pointing something out in front of you.

Both are correct; the second one just gives a stronger sense of this one.

Because after a preposition, Spanish can use either que or article + que in some contexts, especially when referring to a noun.

So these are both possible:

• la calle en que trabajamos
• la calle en la que trabajamos

The version with the article, en la que, often sounds a bit fuller and is very common in careful speech. Since calle is feminine singular, the article is la.

You could think of en la que as literally in/on the one that referring back to calle.

For a learner, donde and en la que are often the easiest patterns to recognise and use.