Si no llevas nada raro, la aduana suele ser rápida, pero aun así conviene tener el pasaporte a mano.

Yes. Llevar often means to carry, to take, or to have on you.

In this sentence, si no llevas nada raro means something like:

• if you aren’t carrying anything unusual
• if you don’t have anything suspicious with you

So it is not just about physically holding something in your hand. It can mean having something in your luggage, pockets, or belongings.

Both verbs can sometimes be possible in travel contexts, but llevar is very natural for talking about what a person has with them.

• llevar = to carry / to have on you
• traer = to bring, usually toward the place where the speaker is

At customs, llevar focuses on what you are carrying. It is the most neutral and common choice here.

Literally, it means nothing strange or nothing unusual.

In context, it usually implies:

• nothing suspicious
• nothing prohibited
• nothing that could cause questions at customs

So raro here does not necessarily mean weird in a humorous sense. It suggests something that might attract attention.

Because the sentence is negative:

• Si no llevas nada raro = If you aren’t carrying anything unusual

After no, Spanish normally uses nada for anything / nothing, depending on the context.

Compare:

• Llevas algo raro = You’re carrying something unusual
• No llevas nada raro = You’re not carrying anything unusual

This is a very common pattern in Spanish.

It can refer to customs in general, or the customs checkpoint/process.

So la aduana suele ser rápida means:

• customs is usually quick
• going through customs is usually quick

Spanish often uses a singular noun where English uses a broader expression.

Because soler + infinitive means to usually do something.

So:

• es rápida = it is quick
• suele ser rápida = it is usually quick

Using suele ser makes the statement less absolute. It suggests what normally happens, not what always happens.

Soler is followed by an infinitive and expresses habitual action.

Here:

• suele = third person singular of soler
• ser = infinitive

So la aduana suele ser rápida literally means customs usually tends to be quick, though in natural English we would just say customs is usually quick.

Common examples:

• Suelo ir en tren. = I usually go by train.
• Suelen llegar tarde. = They usually arrive late.

Because rápida agrees with la aduana, which is feminine singular.

• la aduana → feminine singular
• adjective must match → rápida

If the noun were masculine, you would use rápido.

It means but even so, but still, or but nevertheless.

It adds a contrast:

• customs is usually quick,
• but even so it is still a good idea to keep your passport handy.

So the second part does not contradict the first part completely. It just adds a precaution.

In modern usage, aun así without the accent is the usual spelling in this meaning: even so / nevertheless.

Traditionally:

• aún with accent = still / yet
• un without accent = even / including

In the fixed expression aun así, the meaning is closer to even so, so the unaccented form is standard.

You may still see variation in informal writing, but aun así is the safest choice.

Conviene means something like:

• it is advisable
• it is a good idea
• it is convenient / sensible

So conviene tener el pasaporte a mano means:

• it’s advisable to keep your passport handy
• it’s a good idea to have your passport ready

This is an impersonal structure. Spanish often uses conviene + infinitive to give practical advice without directly telling someone what to do.

Because conviene tener sounds softer and more general.

Compare:

• debes tener = you should have / you must have
• tienes que tener = you have to have
• conviene tener = it’s advisable to have

So conviene is less direct and more like practical advice than an obligation.

Because tener ... a mano is a fixed and very common expression meaning:

• to have something handy
• to keep something within easy reach

So:

• tener el pasaporte a mano = to have the passport handy

You could sometimes use llevar in other contexts, but tener a mano is the natural expression for have ready / have within reach.

Literally, it is something like at hand.

Idiomatic meaning:

• handy
• within reach
• readily available

Examples:

• Ten el móvil a mano. = Keep your phone handy.
• Siempre tengo un diccionario a mano. = I always keep a dictionary handy.

It does not mean literally in your hand. It just means easy to reach.

Spanish often uses the definite article more broadly than English.

So Spanish says:

• la aduana
• el pasaporte
• el tren
• la policía

where English may say:

• customs
• your passport
• by train
• police

Here, la aduana is the normal Spanish way to refer to customs as a general institution or process.

Because Spanish often uses the present tense after si for real, likely conditions.

• Si no llevas nada raro... = If you’re not carrying anything unusual...

Even though this may refer to a future trip, Spanish does not need a future tense here.

This is very common:

• Si vienes mañana, te ayudo. = If you come tomorrow, I’ll help you.
• Si llueve, nos quedamos en casa. = If it rains, we’ll stay home.

So the present tense after si is normal.

It can do both.

The sentence uses llevas, which is the tú form, so grammatically it addresses you directly. But Spanish often uses tú in a general way, like English you meaning any traveler.

So it can mean:

• advice to one specific person, or
• a general statement about what usually happens to people

Both readings are natural.

Yes, it fits Spain Spanish very naturally, though it is understandable everywhere.

A few points:

• llevas uses tú, which is common in Spain and also in many other places
• conviene and a mano are very standard across the Spanish-speaking world
• the overall tone is neutral and widely accepted

So it is not strongly regional in vocabulary, but it sounds completely natural in Spain.