A veces se me olvida el punto final cuando escribo deprisa en el móvil.

Spanish very often expresses forgetting with olvidarse in a kind of something slips my mind structure.

So:

• Olvido el punto final = I forget the full stop
• Se me olvida el punto final = literally something like the full stop forgets itself on me

That literal breakdown sounds strange in English, but it is a very natural Spanish way to say I forget the full stop.

This structure often makes the forgetting sound a bit less deliberate and more like it just happens to you.

In se me olvida:

• me = to me
• se is part of the pronominal verb olvidarse

So the pattern is:

• Se me olvida... = I forget... / ...slips my mind
• Se te olvida... = you forget...
• Se le olvida... = he/she forgets... or it slips his/her mind

Examples:

• Se me olvida tu nombre. = I forget your name.
• Se nos olvidan las llaves. = We forget the keys.

Because the grammatical subject is el punto final, not I.

In this structure, the thing forgotten is the subject:

• el punto final → singular
• so the verb is olvida

Compare:

• Se me olvida el punto final. = I forget the full stop.
• Se me olvidan las llaves. = I forget the keys.

The second one uses olvidan because las llaves is plural.

Because the sentence is talking about the final full stop/period at the end of what you write.

It is one punctuation mark, so singular makes sense:

• el punto final = the final period / full stop

If you were talking about many punctuation marks in general, you might use a plural noun instead.

Here it means the period at the end of a sentence.

In Spain, punto is the usual word for a full stop/period, and punto final specifically emphasizes the final one at the end.

So in this sentence:

• se me olvida el punto final = I forget to put the period at the end

Depending on context, people may also just say el punto.

Good question. There are two common patterns:

1. olvidarse de + noun/infinitive

   • Me olvidé de las llaves.
   • Me olvidé de llamar.

2. olvidársele algo a alguien

   • Se me olvidó el punto final.
   • Se me olvidaron las llaves.

Your sentence uses the second pattern, where the forgotten thing is the grammatical subject, so there is no de.

Both types are common, but they are built differently.

Yes. That is also correct.

The difference is mainly in style and nuance:

• A veces olvido el punto final = more direct, straightforward
• A veces se me olvida el punto final = very natural, often a bit more idiomatic, like it slips my mind

In everyday Spanish, the se me olvida type is extremely common.

A veces means sometimes.

Putting it at the beginning is very natural:

• A veces se me olvida...

But Spanish is flexible, so you could also say:

• Se me olvida a veces el punto final...
• Se me olvida el punto final a veces...

The version with A veces at the start sounds very normal and clear.

Because this sentence describes a habitual/repeated situation, not one specific moment in progress.

• cuando escribo deprisa en el móvil = when I write quickly on my phone
• meaning: whenever that happens, I sometimes forget the period

If you used cuando estoy escribiendo, it would sound more like you are focusing on the action as ongoing in a particular situation. Here the simple present is the normal choice.

Deprisa means quickly / in a hurry.

In this sentence:

• escribo deprisa = I write quickly

It is very common in everyday Spanish.

Compared with rápidamente:

• deprisa sounds a bit more conversational and common in speech
• rápidamente is also correct, but can sound a bit more formal or neutral depending on context

So deprisa is a very natural choice here.

Spanish uses en in many places where English uses on.

So:

• en el móvil = literally in/on the mobile phone
• natural English translation = on my phone

Also, in Spain móvil is the usual word for mobile phone / cell phone.

A learner should avoid translating prepositions too literally. En is simply the normal Spanish choice here.

Spanish often uses the definite article (el, la, los, las) where English would prefer a possessive (my, your, his), especially when the owner is obvious from context.

Here, since escribo already tells us it is I who am writing, el móvil naturally implies my phone.

So both are possible:

• en el móvil = natural
• en mi móvil = also correct, slightly more explicit

It is perfectly understandable across the Spanish-speaking world, but it fits Spain especially well because móvil is very Spain-specific vocabulary for cell phone.

Also, punctuation terms can vary a bit by region:

• Spain: punto, punto final
• many Latin American varieties often use celular instead of móvil

So the whole sentence sounds very natural for Spain Spanish.

Yes, and that is exactly how it is understood in natural English.

Spanish says:

• se me olvida el punto final

But in English we often make the meaning more explicit:

• I forget the final period
• I forget to add the period at the end
• I forget to put a full stop at the end

All of those can match the Spanish sentence depending on how naturally you want to phrase it in English.