L’autobus arriva più tardi del previsto.

Because autobus begins with a vowel sound, Italian normally shortens il to l’ before it.

So:

• il libro
• l’autobus
• l’amico

This is called elision. It makes pronunciation smoother.

Also, autobus is a masculine singular noun, so the full article would be il, not la.

Here it is singular: l’autobus = the bus.

A useful thing to know is that autobus is often treated as invariable in modern Italian, so the singular and plural can look the same:

• l’autobus = the bus
• gli autobus = the buses

The article tells you whether it is singular or plural.

Arriva is the third person singular present tense of arrivare = to arrive.

So l’autobus arriva means:

• the bus arrives
• or, depending on context, the bus is arriving

In this sentence, English usually translates it naturally as the bus is arriving later than expected or the bus arrives later than expected.

Italian often uses the simple present where English might prefer either the simple present or the present progressive.

Because tardi here works as an adverb, not an adjective.

• tardo = late, tardy, late in time period, etc. as an adjective
• tardi = late / later as an adverb

Since it modifies the verb arriva, Italian uses the adverb:

• arriva tardi = it arrives late
• arriva più tardi = it arrives later

You would not use tardo here because that would be the wrong part of speech.

Yes, literally that is the idea: more late. But in natural English, it means later.

Italian often forms comparatives with:

• più = more
• adjective or adverb

So:

• più tardi = later
• più velocemente = more quickly
• più grande = bigger

It is a very common pattern.

Del previsto means than expected or more literally than what was expected.

It breaks down as:

• di = of / than in comparative expressions
• il = the
• del = contraction of di + il
• previsto = expected, foreseen

So più tardi del previsto means later than expected.

This is a very common Italian expression.

Because del is the combination of di + il.

Italian often contracts prepositions with articles:

• di + il = del
• di + lo = dello
• di + la = della
• di + i = dei
• di + gli = degli
• di + le = delle

In del previsto, previsto is being used almost like a noun: the expected, or more naturally, what was expected.

So di + il previsto becomes del previsto.

Previsto is the past participle of prevedere, which means to foresee, to expect, or to plan for, depending on context.

Here, previsto is being used in a very common Italian way: a past participle functioning like a noun or noun-like expression.

So:

• il previsto = the expected thing
• more naturally: what was expected

That is why del previsto can be understood as than what was expected.

You do not need to translate it word for word every time; it is best learned as the set expression più tardi del previsto = later than expected.

Yes, but the meaning is slightly different.

• L’autobus arriva in ritardo. = The bus is late.
• L’autobus arriva più tardi del previsto. = The bus arrives later than expected.

The first focuses on being late in a general sense. The second compares the arrival time with what was expected.

Sometimes they overlap in real life, but they are not exactly identical.

Because this is the normal, straightforward word order in Italian:

• Subject + verb + other information

So:

• L’autobus arriva più tardi del previsto.

Italian can sometimes change word order for style or emphasis, but this sentence uses the most neutral pattern.

A learner should think of it as the standard order: the bus + arrives + later than expected.

A simple pronunciation guide is:

L'OW-to-boos ar-REE-va pyoo TAR-dee del preh-VEE-sto

A few helpful points:

• au in autobus sounds like ow in English now
• arriva has the stress on ri: ar-RI-va
• più sounds like pyoo
• tardi has the stress on tar
• previsto has the stress on vis

Also, the apostrophe in l’autobus means you should connect the words smoothly:
l’autobus, not il autobus.

It can be either, depending on context.

Italian present tense is flexible. It can describe:

• a general fact
• a scheduled event
• something happening now
• a near-future event

So L’autobus arriva più tardi del previsto could mean:

• The bus arrives later than expected
• The bus is arriving later than expected

Context tells you which one is intended. In everyday use, it often refers to the current situation or a scheduled arrival.

Yes. The structure is very useful:

[subject] + [verb] + più + adverb/adjective + del previsto

Examples:

• Il treno parte più presto del previsto.
  The train leaves earlier than expected.

• La riunione finisce più tardi del previsto.
  The meeting ends later than expected.

• Il film è più lungo del previsto.
  The film is longer than expected.

So this sentence is a good model for many similar ideas.