He de mirar l'horari abans de sortir de casa.

No. He here is not the English pronoun he.

In Catalan, he is the 1st person singular present form of the verb haver when it is used in the structure haver de + infinitive, which expresses obligation or necessity.

So:

• he de = I have to / I must
• has de = you have to
• ha de = he/she/it has to
• hem de = we have to
• heu de = you all have to
• han de = they have to

So He de mirar... means I have to look/check...

The structure haver de + infinitive means to have to, must, or to need to.

In this sentence:

• He de mirar = I have to check / I need to look at

It is a very common Catalan way to express obligation.

Examples:

• He de treballar = I have to work
• Has d’estudiar = You have to study
• Hem de marxar = We have to leave

Because the construction is fixed: haver de + infinitive.

So you do not say:

• He mirar ❌

You say:

• He de mirar ✅

This de is simply part of the grammar pattern used to express obligation.

Literally, mirar often means to look or to watch, but in many contexts it also means to check.

In this sentence, mirar l’horari is best understood as:

• check the schedule/timetable
• or look at the schedule/timetable

So the natural English meaning is probably I have to check the schedule before leaving home.

Because Catalan usually elides the article el before a word beginning with a vowel or mute h.

So:

• el horari becomes l’horari

This is similar to:

• l’amic = the friend
• l’escola = the school
• l’hotel = the hotel

Since horari begins with h, and that h is silent, Catalan uses l’.

Here horari means schedule, timetable, or hours depending on context.

In mirar l’horari, it usually means:

• the timetable
• the schedule
• opening hours / times

For example:

• l’horari del tren = the train timetable
• l’horari de la botiga = the shop’s opening hours

So in this sentence it means some kind of schedule the speaker needs to check.

Because after abans when followed by a verb, Catalan normally uses de:

• abans de + infinitive

So:

• abans de sortir = before leaving
• abans de menjar = before eating
• abans de començar = before starting

This is the standard structure.

In sortir de casa, the de means from.

So:

• sortir = to go out / to leave
• sortir de casa = to leave home / go out from home

This is a normal use of de to show origin or the place someone is leaving.

So the sentence contains two different des with different roles:

• he de mirar → part of haver de + infinitive
• abans de sortir → before + infinitive
• sortir de casa → leave from home

Because casa in expressions like anar a casa and sortir de casa often means home, not the house in a literal sense.

So:

• de casa = from home
• a casa = home

Examples:

• Vaig a casa = I’m going home
• Surto de casa a les vuit = I leave home at eight

If you say de la casa, it sounds more like from the house as a physical building, not the general idea of home.

It can mean both, depending on context.

• sortir = to go out
• sortir = to leave

In abans de sortir de casa, the most natural English translation is before leaving home.

But in another context:

• Sortim aquesta nit = We’re going out tonight

So the exact translation depends on what follows.

The sentence is:

• He de mirar l’horari abans de sortir de casa.

A simple breakdown is:

• He de mirar = I have to check
• l’horari = the schedule
• abans de sortir de casa = before leaving home

So the overall order is very similar to English:

I have to check the schedule before leaving home.

Catalan word order here is straightforward and natural.

It already sounds natural and normal.

A speaker might also say something very similar like:

• He de consultar l’horari abans de sortir de casa.
• He de mirar els horaris abans de sortir.

But He de mirar l’horari abans de sortir de casa is perfectly idiomatic.

In casual speech, pronunciation may contract smoothly, especially around vowels:

• l’horari
• abans de sortir
• de casa

But grammatically the sentence is completely standard.

A broad pronunciation guide is:

eh duh mee-RAH luh-ruh-RAH-ree ah-BANS duh soor-TEER duh KAH-zuh

A few useful notes:

• He sounds roughly like eh
• mirar is stressed on the last syllable: mi-RAR
• horari is stressed on the second-to-last syllable: ho-RA-ri
• sortir is stressed on the last syllable: sor-TIR
• casa sounds like CA-sa, with s pronounced like a voiced z in many varieties

Exact pronunciation varies somewhat across Catalan-speaking regions, but this will help you recognize and say it.