Los vecinos desfilan con confeti y farolillos.

Los is the masculine plural definite article, meaning the.

So los vecinos means the neighbors.

Spanish uses definite articles very often before nouns, including people:

• los vecinos = the neighbors
• los niños = the children
• los profesores = the teachers

In this sentence, it refers to a specific group: the neighbors.

Not necessarily. Vecinos is the masculine plural form, and in Spanish that can refer to:

• a group of men, or
• a mixed group of men and women

If the group were only female, you would usually say las vecinas.

Also, vecino/a can mean:

• neighbor
• sometimes local resident, depending on context

So here los vecinos could mean the neighbors or the local residents.

The base form is desfilar, which means to parade or to march in procession.

Desfilan is the third person plural form:

• ellos desfilan = they parade
• los vecinos desfilan = the neighbors parade

It is the present tense.

So Los vecinos desfilan literally means The neighbors parade.

But in English, depending on context, you might naturally translate it as:

• The neighbors are parading
• The neighbors parade

Spanish present tense often covers both the simple present and the present continuous idea that English separates.

Because the subject is los vecinos, which is plural.

Spanish verbs must agree with the subject:

• el vecino desfila = the neighbor parades
• los vecinos desfilan = the neighbors parade

So:

• singular subject -> desfila
• plural subject -> desfilan

Con means with.

So con confeti y farolillos means with confetti and lanterns.

In this sentence, con tells you what accompanies the parade or what the neighbors have around them / are using during it.

Spanish often leaves out the article when talking about things in a general way, especially after con.

So:

• con confeti = with confetti
• con farolillos = with lanterns
• con confeti y farolillos = with confetti and lanterns

A few useful points:

• confeti is usually treated like a mass noun, similar to confetti in English
• farolillos is a plural count noun: little lanterns

You could sometimes add articles in other contexts, but here no article sounds natural.

Farolillos are small lanterns, often decorative ones used at festivals, fairs, and celebrations.

The word comes from:

• farol = lantern
• -illo = a diminutive ending, often meaning small or little

So farolillos literally means little lanterns.

In Spain, this word often suggests festive decorative lanterns, especially the colorful paper ones seen at local celebrations.

The ending -illo is a diminutive. It often gives the idea of:

• small size
• affection
• something cute or informal

So:

• farol = lantern
• farolillo = little lantern

Then farolillos is the plural.

Diminutives are very common in Spanish, although they do not always translate literally into English. Depending on context, farolillos might simply be translated as lanterns, even though the Spanish form is technically little lanterns.

Spanish can often omit subject pronouns, but here los vecinos is a noun phrase, not a pronoun, and it is included to make clear who is parading.

You could say:

• Desfilan con confeti y farolillos.

That would mean They parade / are parading with confetti and lanterns, but only if the context already makes clear who they are.

By saying Los vecinos desfilan..., the sentence explicitly names the subject.

Yes, it is fairly straightforward here:

• Los vecinos = subject
• desfilan = verb
• con confeti y farolillos = prepositional phrase

So the structure is basically: The neighbors + parade + with confetti and lanterns

Spanish word order can be more flexible than English, but this sentence uses a very normal and neutral order.