En la última página del informe, dejé una columna en blanco para añadir otro apartado si mi tutora lo pedía.

Because en is the normal preposition for location on/in a page: en la página, en el informe, en el documento.

Here, En la última página del informe means On the last page of the report.

• en la página 3 = on page 3
• en el informe = in the report

Using a would usually suggest movement toward something, not location.

Del is the contraction of de + el.

So:

• de el informe → del informe

It means of the report:

• la última página del informe = the last page of the report

This contraction is mandatory with de + el, except when el is part of a proper name.

Dejé is the pretérito indefinido of dejar: I left.

It is used because the speaker is referring to a completed action in the past: they left a blank column on the page at a specific moment while preparing the report.

So:

• dejé = I left
• completed past action

If you used the imperfect, dejaba, it would sound more like background information, habit, or an ongoing action, which does not fit as well here.

It means I left a blank column.

The structure dejar + something + en blanco is very common in Spanish and means to leave something blank / empty.

Examples:

• Dejé una casilla en blanco. = I left a box blank.
• No dejes preguntas en blanco. = Don’t leave questions blank.

So here:

• una columna = a column
• en blanco = blank

Because en blanco is a fixed expression meaning blank or left empty.

Compare:

• una página blanca = a white page
• una página en blanco = a blank page

So blanco/blanca by itself usually describes colour, while en blanco describes the state of being unfilled or empty.

Para + infinitive expresses purpose: in order to, so as to, to.

So:

• dejé una columna en blanco para añadir otro apartado = I left a blank column in order to add another section

It explains why the speaker left the blank space.

This is a very common Spanish structure:

• Fui al supermercado para comprar pan.
• Abrí el archivo para revisarlo.

In this context, apartado means something like section, subsection, or heading in a document.

So otro apartado means another section.

This word is especially common in formal or academic writing in Spanish from Spain.

Depending on context, apartado can also mean:

• a section of a form
• a paragraph or division in a text
• even a post office box in other contexts (apartado de correos)

But here it clearly refers to a section of the report.

Because in Spanish, otro normally does not take the indefinite article.

So you say:

• otro apartado = another section
• otra página = another page

Not:

• un otro apartado ❌

This is one of the differences from English, where another historically contains the article idea already.

This is a very common question. The imperfect pedía is used because the sentence is talking about a possible or contextual situation in the past: if my supervisor asked for it / were to ask for it.

The main idea is not that she definitely asked for it once, but that the speaker left space available in case that need arose.

So:

• si mi tutora lo pedía = if my supervisor asked for it / should ask for it
• si mi tutora lo pidió would sound more like if my supervisor asked for it on that specific occasion, referring to a completed event

The imperfect often appears in this kind of background or contingency meaning in past narration.

Lo is a direct object pronoun meaning it.

Here, it refers to the idea of adding that extra section, or more generally that request.

So:

• mi tutora lo pedía = my supervisor asked for it

Spanish often uses lo when English might say it, that, or even leave it more implicit.

Because tutora is the feminine form of tutor.

It means the supervisor/tutor/adviser is female.

• mi tutor = my male tutor/supervisor
• mi tutora = my female tutor/supervisor

In academic contexts in Spain, tutor/tutora can refer to the person supervising your work or guiding your studies.

Yes. Dejar is very flexible and often works like English leave.

Here it means to leave something in a certain state:

• dejar una columna en blanco = to leave a column blank
• dejar la puerta abierta = to leave the door open
• dejar el móvil en casa = to leave the phone at home

So this use is completely natural.

It is natural and helpful here because En la última página del informe is an introductory phrase giving context.

So the comma separates the setting from the main clause:

• En la última página del informe, dejé...

Without the comma, the sentence would still be understandable, but the version with the comma is clearer and better punctuated.

Yes, and in many contexts por si would sound even more explicit.

• si = if
• por si = in case

So:

• dejé una columna en blanco si mi tutora lo pedía = if my supervisor asked for it
• dejé una columna en blanco por si mi tutora lo pedía = I left a blank column in case my supervisor asked for it

In this sentence, por si highlights precaution more clearly. But si is still understandable in the intended meaning.

It breaks down like this:

• En la última página del informe = location/context
• dejé una columna en blanco = main action
• para añadir otro apartado = purpose
• si mi tutora lo pedía = condition or possible circumstance

So the logic is:

On the last page of the report, I left a blank column in order to add another section if my supervisor asked for it.

This is a good example of how Spanish can stack pieces of information in a very compact but natural way.