Has de recordar on és el telèfon abans de sortir.

Has de means you have to or you must.

It is a very common Catalan way to express obligation:

• He de = I have to
• Has de = you have to
• Ha de = he/she has to
• Hem de = we have to
• Heu de = you all have to
• Han de = they have to

So:

• Has de recordar... = You have to remember...

This is built with haver + de + infinitive.

Catalan commonly uses haver de + infinitive to mean have to / must.

So:

• Has de recordar = You have to remember

You may also hear tenir que in some informal speech, especially under Spanish influence, but standard Catalan strongly prefers haver de.

So for learners, has de + infinitive is the safest and most standard choice.

Because the obligation structure is:

• haver + de + infinitive

So the de is part of the grammar, not optional.

Examples:

• Has de venir = You have to come
• Hem de marxar = We have to leave
• Ha de ploure = It must / has to rain

Without de, the sentence would be ungrammatical in standard Catalan.

In Catalan, recordar usually works directly as a normal verb meaning to remember.

So:

• Recordo el teu nom = I remember your name
• Has de recordar on és el telèfon = You have to remember where the phone is

Catalan also has recordar-se de, which is another common way to say remember, especially in some contexts:

• Recorda’t de les claus = Remember the keys
• Me’n recordo = I remember

But in your sentence, recordar without a reflexive pronoun is completely natural.

On means where.

In this sentence:

• on és el telèfon = where the phone is

It introduces an indirect question, not a direct one.

Compare:

• On és el telèfon? = Where is the phone?
• Has de recordar on és el telèfon. = You have to remember where the phone is.

Because it is an indirect question inside a larger sentence.

Direct question:

• On és el telèfon?

Indirect question:

• Has de recordar on és el telèfon.

English does the same:

• Direct: Where is the phone?
• Indirect: You have to remember where the phone is.

Notice that the word order stays normal in Catalan here, just like in English indirect questions.

This is a very common question for learners.

In Catalan, ser is often used to indicate where something is, especially when simply identifying its location:

• On és el telèfon?
• El telèfon és a la taula.

This is different from Spanish, where estar is usually used for location.

Catalan does have estar, but it is used more selectively, often with nuances such as state, condition, emphasis on being placed somewhere, or temporary situations. In many basic location questions, ser is the normal choice.

So on és el telèfon is exactly what you should expect in Catalan.

Abans de means before when it is followed by an infinitive.

So:

• abans de sortir = before leaving / before you leave

This is a fixed pattern:

• abans de + infinitive

Examples:

• Abans de menjar = Before eating
• Abans de dormir = Before sleeping
• Abans de marxar = Before leaving

Because when abans is followed by an infinitive, Catalan normally uses de:

• abans de sortir
• abans de parlar
• abans de començar

So de is required here.

If a full clause follows instead, Catalan can use abans que:

• Abans que surtis = Before you leave

So the difference is:

• abans de + infinitive
• abans que + conjugated verb

Sortir means to go out, to leave, or to exit, depending on context.

In this sentence:

• abans de sortir = before leaving / before going out

A few examples:

• Surto de casa = I leave the house
• Volem sortir ara = We want to go out now
• Ha sortit de l’habitació = He/She left the room

So here it simply means leaving the place.

Because Catalan often leaves subject pronouns out when the verb already makes the subject clear.

• Has de recordar... already tells you the subject is you singular.

If you wanted, you could say:

• Tu has de recordar...

But tu is usually only added for emphasis, contrast, or clarity.

This is very normal in Catalan:

• Parlo = I speak
• Vens? = Are you coming?
• Hem de marxar = We have to leave

Sometimes in context it might feel similar, but the basic meaning is stronger: you have to remember.

• Has de recordar = obligation / necessity
• Hauries de recordar = you should remember

So if you specifically want the softer English idea should, Catalan would normally use a different form, such as hauries de.

It can mean either the phone or the telephone, depending on context.

In modern everyday English, the phone is usually the best translation.

• telèfon = phone / telephone

So:

• on és el telèfon = where the phone is

You would change has de to he de:

• He de recordar on és el telèfon abans de sortir.
• I have to remember where the phone is before leaving.

The rest of the sentence stays the same.

The sentence breaks down like this:

• Has de recordar = You have to remember
• on és el telèfon = where the phone is
• abans de sortir = before leaving

So the full structure is:

• [obligation] + [thing to remember] + [time expression]

Or more literally:

• You-have-to remember where is the phone before to-leave

But natural English is:

• You have to remember where the phone is before leaving.