El pato camina despacio por el barro.

El is the masculine singular definite article, meaning the.

• el pato = the duck
• el barro = the mud

In Spanish, articles are used more often than in English. Here, both nouns are masculine singular, so el is the correct article for each one.

Also, barro is treated as a specific substance or setting in the sentence, so el barro sounds natural.

Camina is the third-person singular present tense form of the verb caminar.

The subject is el pato = the duck, which is he/it in grammatical terms, so Spanish uses:

• caminar = to walk
• camina = he/she/it walks

So El pato camina means The duck walks or The duck is walking, depending on context.

Despacio is an adverb, and it means slowly.

It modifies the verb camina, telling us how the duck walks:

• camina = walks
• camina despacio = walks slowly

A common beginner mistake is to look for an adjective like lento here, but after a verb you need the adverb:

• lento = slow
• despacio or lentamente = slowly

Yes. El pato camina lentamente por el barro is also correct.

The difference is mainly style and frequency:

• despacio is very common and natural in everyday speech
• lentamente is also correct, but can sound a little more formal or descriptive

For a learner, despacio is a very useful everyday word.

In Spanish, adverbs often come after the verb, especially in simple sentences like this one.

So:

• camina despacio = walks slowly

This is the most natural order here. Spanish word order is somewhat flexible, but El pato camina despacio por el barro sounds very normal and straightforward.

You might also hear:

• El pato despacio camina...

but that sounds marked or poetic, not the usual everyday order.

Here, por suggests movement through, along, or across an area.

So por el barro means something like:

• through the mud
• across the mud
• along in the mud, depending on context

Why not en?

• en el barro focuses more on being in the mud
• por el barro focuses more on moving through the mud

Because the duck is walking, por is the natural choice.

Because Spanish only has two mandatory contractions:

• a + el = al
• de + el = del

But:

• por + el = por el

So por el barro stays exactly like that. There is no contraction.

Because barro is a masculine noun in Spanish, so it takes el:

• el barro

For many nouns, grammatical gender has to be learned together with the word. There is not always a logical reason from an English speaker’s point of view.

A good habit is to learn new nouns with their article:

• el pato
• el barro

That helps you remember gender naturally.

In standard Spain pronunciation, despacio is pronounced roughly like des-PA-thyo.

Important points:

• the c before i is usually pronounced like the th in think
• so -cio sounds like thyo
• camina has a normal k sound at the beginning
• barro has a strong rolled rr

So a Spain pronunciation would be approximately:

• El pato camina despacio por el barro
• el PA-to ka-MEE-na des-PA-thyo por el BA-rro

In Spanish, rr represents a trilled/rolled r sound.

That is different from a single r between vowels, which is usually a softer tap.

Compare:

• caro = expensive
• carro = cart/car

So in barro, the rr is important both for pronunciation and spelling.

Yes. Spanish often leaves out the subject when it is clear from the verb or context.

So if everyone already knows we are talking about the duck, you could say:

• Camina despacio por el barro.

That still means It walks slowly through the mud or The duck walks slowly through the mud, depending on context.

Spanish does this much more often than English.

Yes. The Spanish present tense often covers both ideas:

• walks
• is walking

So El pato camina despacio por el barro could mean:

• The duck walks slowly through the mud
• The duck is walking slowly through the mud

The exact meaning depends on context.

If you want to be very explicit about is walking, Spanish can also use:

• El pato está caminando despacio por el barro.

But the simple present is very common and natural.

Sometimes, yes, but the meaning changes slightly.

• camina focuses specifically on walking
• anda can mean walks, goes, or moves around, depending on context

So:

• El pato camina despacio por el barro = the duck walks slowly through the mud
• El pato anda despacio por el barro = also possible, but a little less specifically about the act of walking

For a basic, clear sentence, camina is the most direct choice.