O terreno está molhado, e o calçado também.

Because estar is used for a state or condition, especially one that can change. Wetness is temporary, so Portuguese uses estar molhado.

• O terreno está molhado = the ground is wet
• É molhado would sound like you are describing something as inherently or characteristically wet, which is not the idea here.

So this is a classic ser vs. estar choice: use estar for a temporary condition.

Because molhado agrees with the noun it describes, and both nouns here are masculine singular:

• o terreno → masculine singular
• o calçado → masculine singular

So the adjective must also be masculine singular: molhado.

If the noun were feminine, you would use molhada:

• A terra está molhada.

If it were plural:

• Os sapatos estão molhados.
• As botas estão molhadas.

Terreno usually means plot of land, piece of ground, lot, terrain, land area. In this sentence, it refers to the ground/land surface being wet.

Depending on context, other words could also be used:

• chão = floor / ground
• terra = earth / soil / dirt
• terreno = land, lot, terrain, plot

So terreno sounds a bit more like the land/ground area, not just the floor.

Because calçado can function as a collective or general noun meaning footwear. In that use, it is grammatically singular even though it may refer to something worn on both feet.

So:

• o calçado = footwear / shoe(s), in a general sense

This is different from saying:

• os sapatos = the shoes
• o sapato = the shoe

Using o calçado is a bit more general and sometimes slightly more formal or neutral than naming a specific item like sapato or tênis.

Because Portuguese, like English, often omits words that are already understood from the first clause.

So:

• O terreno está molhado, e o calçado também.

means:

• O terreno está molhado, e o calçado também está molhado.

This omission is very natural. It avoids repetition.

English does the same thing:

• The ground is wet, and the footwear is too.

Here também means also / too. In an elliptical structure like this, putting também after the noun phrase is very natural:

• e o calçado também

It means and the footwear too / also.

You could also say:

• e o calçado também está molhado
• e também o calçado está molhado — possible, but less natural here
• e o calçado está molhado também — also possible

The version in your sentence is compact and very idiomatic.

Yes. That is grammatically correct.

But it sounds more repetitive because molhado was already said. Native speakers often prefer the shorter version:

• O terreno está molhado, e o calçado também.

Both are correct. The shorter one is simply more elegant and natural in many contexts.

Portuguese uses definite articles more often than English does. So where English might say ground or footwear with no article, Portuguese often says:

• o terreno
• o calçado

Here the article can make the nouns sound more definite, generic, or contextually understood.

In many cases, leaving the article out would sound less natural or would slightly change the tone.

Not always. Portuguese can use a comma before e when joining two clauses, especially if there is a slight pause or if the second part has some contrast or added emphasis.

So both are possible:

• O terreno está molhado e o calçado também.
• O terreno está molhado, e o calçado também.

With the comma, the sentence may feel a little more carefully separated or stylistically polished. Without it, it is still perfectly normal.

Yes, but the wording may sound slightly different.

Possible versions:

• O terreno está molhado, e o calçado também.
• O terreno está molhado, e o calçado também está molhado.
• O terreno está molhado, e o calçado está molhado também.

These are all understandable. The original version is especially natural because também neatly replaces the repeated information.

Yes, depending on what you mean.

• o calçado = the footwear
• o sapato = the shoe
• os sapatos = the shoes

Examples:

• O terreno está molhado, e os sapatos também.
• O terreno está molhado, e o sapato também.

If you are talking about footwear in a general sense, calçado works well. If you mean actual shoes, sapato or sapatos may be more specific and more common in everyday speech.

The ç is called cedilha in Portuguese. It makes the c sound like s before a, o, or u.

So:

• ca normally sounds like ka
• ça sounds like sa

That is why calçado is pronounced with an s sound in the middle, not a k sound.

Without the cedilla, calcado would suggest a different pronunciation and would not be the correct spelling of this word.

The accent mark in também shows the stressed syllable: -bém.

In Brazilian Portuguese, it is pronounced approximately like:

• tam-BENG or tam-BEIN depending on how roughly you approximate it in English

The final sound is nasal, which English does not really have in the same way. The accent also helps distinguish the word’s stress pattern.

So também is not flatly pronounced; the stress is clearly on the last syllable.

It is mostly neutral.

• terreno is neutral
• calçado is a bit more general and can sound slightly more formal or technical than sapato
• the structure itself is completely normal and natural

In very casual everyday speech, many people might say something more concrete, such as:

• O chão está molhado, e os sapatos também.

But your original sentence is still perfectly good, natural Portuguese.