Pongo un recordatorio en el móvil para no olvidar la cita.

In Spanish, subject pronouns are often left out because the verb ending already shows who the subject is.

• pongo = I put / I set
• The -o ending tells you it is yo

So Pongo un recordatorio... is completely natural.
You could say Yo pongo un recordatorio..., but that usually adds emphasis, contrast, or clarity.

For example:

• Pongo un recordatorio. = neutral
• Yo pongo un recordatorio, pero él no. = I set a reminder, but he doesn’t

Pongo is the present indicative of poner.

Here it can mean:

• I set a reminder
• I’m setting a reminder
• sometimes even I usually set a reminder, depending on context

Spanish present tense is often broader than English present tense, so one form can match several English possibilities.

Because poner is irregular in the yo form.

Its present tense is:

• yo pongo
• tú pones
• él/ella pone
• nosotros ponemos
• vosotros ponéis
• ellos/ellas ponen

Many Spanish verbs have this -go pattern in the first person singular, especially common verbs such as:

• hacer → hago
• tener → tengo
• salir → salgo
• venir → vengo

So pongo is just the normal irregular yo form of poner.

Literally, poner often means to put, but in many contexts it is used more broadly.

In this sentence, poner un recordatorio means something like:

• to set a reminder
• to put in a reminder
• to create a reminder

This is a very common use of poner in Spanish, especially with apps, alarms, music, tables, clothes, and so on.

Examples:

• Pongo una alarma. = I set an alarm.
• Pongo música. = I put on some music.
• Pongo la mesa. = I set the table.

Because recordatorio is a masculine singular countable noun.

• un = masculine singular indefinite article
• recordatorio = reminder

So:

• un recordatorio = a reminder

It is masculine because the noun is masculine, not because of anything about the object itself.
If the noun were feminine, you would use una instead.

In Spain, el móvil means the mobile phone / cell phone.

So en el móvil literally means in/on the phone. In natural English, we would usually say on my phone.

Spanish often uses en in places where English uses on.

Examples:

• en el móvil = on the phone
• en internet = on the internet
• en la lista = on the list

Spanish often uses the definite article (el, la, los, las) where English would prefer a possessive like my.

So en el móvil can naturally mean:

• on the phone
• on my phone, if the context already makes that obvious

If you want to be more explicit, you can absolutely say:

• en mi móvil

Both are possible, but en el móvil sounds very natural when it is clear whose phone is meant.

Yes, móvil is especially the usual word in Spain for mobile phone.

In much of Latin America, people more often say:

• celular
• sometimes teléfono

So a Latin American version might be:

• Pongo un recordatorio en el celular...

Both are correct Spanish, but móvil strongly sounds like Spain Spanish.

Para here expresses purpose: in order to / so as to.

So:

• para no olvidar la cita = so as not to forget the appointment

This is a very common Spanish structure:

• para + infinitive

Examples:

• Estudio para aprender. = I study to learn.
• Te llamo para confirmar. = I’m calling you to confirm.
• Pongo un recordatorio para no olvidar. = I set a reminder so I don’t forget.

Because the subject of both actions is the same person (I set, I forget / don’t forget), Spanish uses para + infinitive.

Because in Spanish, when you negate an infinitive, no goes directly before it.

So:

• olvidar = to forget
• no olvidar = not to forget

That is why you get:

• para no olvidar = in order not to forget

This is the normal pattern.

Both are possible, but they work a little differently.

1. olvidar algo

This is the simple transitive form:

• olvidar la cita = to forget the appointment

2. olvidarse de algo

This is a pronominal version, also very common:

• olvidarse de la cita = to forget about the appointment

In this sentence, olvidar la cita is direct and natural.
If you changed it, you would say:

• Pongo un recordatorio en el móvil para no olvidarme de la cita.

Notice that with olvidarse, you need the pronoun too: olvidarme.

Because it refers to a specific appointment/date that the speaker already has in mind.

• la cita = the appointment / the date
• una cita = an appointment / a date, not yet specific

Using la suggests the appointment is known in the situation. That matches the idea of setting a reminder for a particular event.

No. Cita can mean several things depending on context:

• appointment
• date (romantic)
• quotation / quote

In this sentence, because of recordatorio and no olvidar, the most natural meaning is probably appointment, though date is also possible if the context is personal.

The given order is very natural, but Spanish word order is fairly flexible.

Original:

• Pongo un recordatorio en el móvil para no olvidar la cita.

Possible variation:

• Pongo en el móvil un recordatorio para no olvidar la cita.

That is still grammatical, but the original sounds smoother and more neutral in everyday speech.

Spanish often changes word order for rhythm, focus, or emphasis, but not every possible order sounds equally natural.

A very natural English translation would be:

• I set a reminder on my phone so I don’t forget the appointment.

That helps show a few things:

• poner un recordatorio often corresponds to set a reminder
• en el móvil often becomes on my phone
• para no olvidar often becomes so I don’t forget

So the Spanish is not translated word-for-word in the most natural English, even though the structure is easy to follow.