El chico compra un billete de ida y vuelta.

In Spanish, you usually need an article before a singular countable noun when you mean the boy or a boy.

• el chico = the boy
• un chico = a boy

Using just chico by itself would not sound natural here as the subject of a normal sentence.

Because chico is a masculine singular noun.

Spanish articles must agree with the noun:

• el = masculine singular
• la = feminine singular
• los = masculine plural
• las = feminine plural

So:

• el chico = the boy
• la chica = the girl

Compra is the third person singular of the present tense of comprar.

So it means:

• he/she buys
• and in this sentence, specifically the boy buys

Conjugation of comprar in the present:

• yo compro
• tú compras
• él/ella/usted compra
• nosotros compramos
• vosotros compráis
• ellos/ellas/ustedes compran

Because comprar is the infinitive, meaning to buy.
In a full sentence with a subject, Spanish normally uses a conjugated verb.

• comprar = to buy
• compra = he/she buys

So:

• El chico compra... = The boy buys...

If you said El chico comprar..., that would be ungrammatical.

Un billete means a ticket, while el billete means the ticket.

Here, un introduces the ticket as something unspecified or not previously mentioned.

• compra un billete = buys a ticket
• compra el billete = buys the ticket

So the sentence is talking about a ticket, not a specific one already known to the listener.

Here, billete means ticket, especially for travel.

In Spain, billete is the normal word for a transport ticket, such as:

• billete de tren = train ticket
• billete de avión = plane ticket

Be aware that billete can also mean banknote in other contexts, so the meaning depends on the sentence.

Because de ida y vuelta is a fixed expression meaning return ticket or round-trip ticket.

Literally, it is:

• ida = outbound journey / going
• vuelta = return
• de ida y vuelta = for going and returning

So un billete de ida y vuelta means a return ticket.

Spanish uses de here as part of the expression linked to billete.

On their own:

• ida comes from the idea of going or outbound travel
• vuelta means return, way back, or sometimes turn/lap depending on context

In travel language:

• billete de ida = one-way ticket
• billete de ida y vuelta = return / round-trip ticket

So this is very common vocabulary for transport.

It is widely understood, but vocabulary can vary by region.

In Spain:

• billete is very common for ticket

In many Latin American countries, people often use:

• boleto
• pasaje in some contexts

But ida y vuelta is broadly understood.
A learner focusing on Spain should definitely know billete de ida y vuelta.

Because the normal basic Spanish sentence order is:

Subject + Verb + Object

So here:

• El chico = subject
• compra = verb
• un billete de ida y vuelta = object

This matches the normal English structure:

• The boy buys a return ticket

Spanish can change word order for emphasis, but this version is the most neutral and standard.

Yes. Spanish often omits subject pronouns, and sometimes even noun subjects if the context is clear.

• Compra un billete de ida y vuelta could mean He buys a return ticket, She buys..., or You (formal) buy..., depending on context.

But in your sentence, El chico is included to make it explicit who is buying the ticket.

Spanish often expresses the same idea with a phrase rather than a single adjective.

English says:

• a round-trip ticket
• a return ticket

Spanish commonly says:

• un billete de ida y vuelta

So instead of one compact modifier, Spanish uses a descriptive expression: ticket for going and coming back.

You would say:

• un billete de ida

That contrasts with:

• un billete de ida y vuelta = return / round-trip ticket

So the pattern is very useful:

• ida = one way / outbound
• ida y vuelta = there and back / return

Not always. Chico can mean:

• boy
• lad
• guy
• young man, depending on context

In a simple learner sentence, boy is the most straightforward translation. But in real life, the exact English word may change depending on age and tone.

A rough pronunciation is KOM-pra.

Very approximately for an English speaker:

• com- like comb without the final b sound
• -pra with a tapped Spanish r

The stress is on the first syllable:

• COM-pra

And a few notes:

• c before o sounds like k
• r in pra is not the English r; it is a light tap

Usually in this sentence, no. Billete here is specifically ticket.

A pass in English often means something different, such as:

• a travel pass
• a season pass
• an access pass

Spanish might use other words depending on the context, such as abono for a travel pass. So here, ticket is the best choice for billete.