Hice un borrón al escribir deprisa, pero terminé corrigiéndolo con calma.

Hice is the pretérito indefinido form of hacer for yo: I made / I did.

In this sentence, the speaker is referring to one completed action in the past: they made a blot / mistake while writing quickly. That is why hice fits well.

• hacer → hice
• similar idea: I made a mistake / I made a blot

A learner may expect cometí un error, but Spanish also uses hacer in expressions like this:

• hacer un borrón
• hacer una pausa
• hacer una pregunta

So hice un borrón is structurally very normal.

Borrón literally suggests a smudge, blot, scribble, or messy mark, especially in writing. In context, it can also imply a writing slip or messy mistake on the page, not just an abstract error.

So it is a bit more physical and visual than a general word like error.

Compare:

• un error = an error, mistake in general
• un borrón = a blot, smudge, messy written mark

Because the sentence mentions writing quickly, borrón feels especially natural: it suggests the kind of untidy mistake you make on paper when your hand moves too fast.

Because in Spanish, countable nouns usually need an article or determiner when you mention one instance of something.

So:

• Hice un borrón = I made a blot / a messy mark

Leaving out un would sound incomplete in normal Spanish.

This is similar to:

• Cometí un error
• Tuve un problema
• Hice una marca

Spanish often requires an article where English sometimes feels more flexible.

Al + infinitive is a very common Spanish structure. It often means:

• when ...
• while ...
• upon ...
• sometimes by ...ing, depending on context

Here, al escribir means something like:

• when writing
• while writing

So the structure is:

• al = a + el
• escribir = to write

Examples:

• Al entrar, saludó a todos. = When entering / Upon entering, he greeted everyone.
• Al estudiar, escucho música. = When I study / While studying, I listen to music.

In your sentence, al escribir deprisa gives the circumstance in which the blot happened.

Both are possible, but deprisa is very common and natural, especially in everyday Spanish.

• escribir deprisa = to write quickly / in a hurry
• escribir rápidamente = to write quickly

The difference is mostly one of style and feel:

• deprisa sounds more everyday and conversational
• rápidamente can sound a bit more neutral or formal

In Spain, deprisa is extremely common in speech.

You will also hear:

• rápido used adverbially in informal speech: Escribe rápido
• con prisa = in a hurry

But deprisa is a very natural choice here.

In modern standard Spanish, deprisa is normally written as one word.

• deprisa = quickly, hurriedly

You may occasionally see variation in older texts or nonstandard writing, but for a learner, the safe standard form is:

• deprisa

Examples:

• Habla deprisa.
• Iba deprisa.
• Escribí deprisa y me equivoqué.

Terminar + gerundio often means to end up doing something or to finally do something after a process.

So:

• terminé corrigiéndolo = I ended up correcting it / I finally corrected it

This construction gives a sense of progression:

1. first, the speaker made the blot
2. later, they eventually corrected it

It is not just a plain past action; it highlights the final result.

Compare:

• Lo corregí. = I corrected it.
  Plain statement of fact.
• Terminé corrigiéndolo. = I ended up correcting it / I finally got around to correcting it.
  More sense of process or eventual outcome.

Yes, but the meaning changes slightly.

• terminé corrigiéndolo = I ended up correcting it / I finally corrected it
• terminé de corregirlo = I finished correcting it

The second one focuses more on completion of the correction itself. The first one focuses more on the fact that, after the blot happened, the speaker eventually did correct it.

So in this sentence, terminé corrigiéndolo works well because it contrasts nicely with the earlier mistake:

• I made a mess writing quickly, but in the end I corrected it calmly.

Lo refers back to un borrón.

Since borrón is a masculine singular noun, the direct object pronoun is:

• lo

So:

• corrigiendo + lo → corrigiéndolo

Literally, this is correcting it.

Even though borrón is a blot/smudge, Spanish can still use corregir with it in context, because the idea is that the speaker fixed the written mistake or untidy mark.

Because when pronouns are attached to a gerund, Spanish often adds a written accent to keep the original stress.

Start with:

• corrigiendo

Then attach:

• lo

You get:

• corrigiéndolo

The accent mark shows where the stress stays.

This happens a lot with gerunds and attached pronouns:

• diciendo → diciéndolo
• haciendo → haciéndome
• escribiendo → escribiéndote

So the accent is not optional here; it is part of the correct spelling.

With a gerund, object pronouns can often be attached to the gerund itself:

• terminé corrigiéndolo

In some structures, Spanish may also allow a pronoun earlier in the phrase, but here attaching it to corrigiendo is the most straightforward and natural option.

Also, lo terminé corrigiendo can sound a bit different in rhythm and emphasis, and many learners find terminé corrigiéndolo easier to understand as one unit:

• terminar + gerundio + object

So in this sentence, terminé corrigiéndolo is a very natural formulation.

Yes, literally it is with calm, but idiomatically it means:

• calmly
• carefully
• without rushing
• taking one’s time

It is a very common Spanish expression.

Examples:

• Hazlo con calma. = Do it calmly / Take your time.
• Léelo con calma. = Read it carefully / Read it at your leisure.

In your sentence, con calma contrasts nicely with deprisa:

• first the speaker wrote too quickly
• then they corrected the problem calmly

That contrast is one of the nicest features of the sentence.

Yes, it sounds natural, especially in Spain.

A few points that make it feel very natural:

• deprisa is very common in Spain
• al escribir is a standard, elegant structure
• terminé corrigiéndolo is idiomatic
• con calma is extremely common everyday Spanish

If anything, the sentence has a slightly polished, well-written feel, but it is still completely natural.

Yes, but the meaning would shift a little.

• Hice un borrón suggests a physical writing blot/scribble/messy mark
• Cometí un error suggests a more general mistake

If you say:

• Cometí un error al escribir deprisa...

that is perfectly correct, but it loses the image of a visible mark on the page.

So if the context is handwriting or something physically messy on paper, borrón is a better fit. If the context is just “I made a mistake,” then error is broader.

It could be, but it would not mean exactly the same thing.

• me equivoqué = I made a mistake / I was wrong
• hice un borrón = I made a blot / messy written mark

So me equivoqué is more general. It says the speaker made some kind of mistake, but it does not specifically evoke a written smudge or scribble.

Because the sentence is about writing quickly and then correcting the result, borrón is more concrete and descriptive.