O espeto está na mesa.

Because espeto is a masculine noun in Portuguese, so it normally takes the masculine singular definite article o.

• o espeto = the skewer / the spit
• a mesa = the table

In Portuguese, noun gender is grammatical, so you usually have to learn the noun together with its article.

Because mesa is a feminine noun, so its definite article is a.

• a mesa = the table
• uma mesa = a table

This is why later in the sentence you get na mesa, because na contains the feminine article a.

Portuguese has two main verbs meaning to be: ser and estar.

Here, está is used because the sentence is talking about location:

• O espeto está na mesa. = The skewer is on the table.

For location of people and things, Portuguese normally uses estar, not ser.

Compare:

• A mesa é grande. = The table is big.
  
  • description/characteristic → ser
• A mesa está na cozinha. = The table is in the kitchen.
  
  • location → estar

The accent in está shows the stressed syllable and is also part of the correct spelling.

• está is pronounced with stress on the second syllable: es-TÁ

It also helps distinguish forms in writing. In this case, you should simply learn está as the correct 3rd person singular form of estar:

• eu estou
• você/ele/ela está

Because in Portuguese, em + a normally contracts to na.

So:

• em + a mesa → na mesa

This kind of contraction is very common:

• em + o = no
• em + a = na
• em + os = nos
• em + as = nas

So na mesa literally comes from em a mesa, but native speakers use the contracted form.

In this sentence, na mesa is understood as on the table.

The preposition em (and its contractions like na) has a broad range of meanings, including in, on, or at, depending on context.

So Portuguese often uses em where English makes a sharper distinction.

Examples:

• na mesa = on the table
• na caixa = in the box
• na escola = at school

Because the subject is already expressed as o espeto.

Portuguese does not need an extra dummy subject like English sometimes does. The structure is simply:

• O espeto = subject
• está = is
• na mesa = on the table

So the sentence is complete without adding anything else.

Usually, that would sound unnatural in normal Portuguese.

In Portuguese, articles are used more often than in English, especially with common countable nouns in ordinary statements.

So the natural sentence is:

• O espeto está na mesa.

Without the article, it might sound incomplete, headline-like, or very context-dependent.

In Brazilian Portuguese, espeto is approximately pronounced es-PE-tu.

A rough guide:

• es = like es in especially
• pe = stressed, like peh
• to = often sounds closer to tu in many Brazilian accents

So a rough English-style approximation is es-PEH-too.

Also note:

• the stress is on pe
• the final o in Brazilian Portuguese is often pronounced like u

A natural approximate pronunciation is:

• u es-PE-tu es-TA na ME-zə

A few useful notes:

• o often sounds like u when unstressed: o espeto → u espetu
• está has stress on the last syllable: es-TÁ
• mesa is usually pronounced with a z sound in the middle: ME-zə

This is only an approximation, but it can help you hear the rhythm.

Está is the 3rd person singular form of estar in the present tense.

It is used with:

• ele está
• ela está
• você está
• and also with singular nouns like o espeto

So in O espeto está na mesa, the noun o espeto matches the singular verb está.

Yes, but the basic order subject + verb + location is the most neutral and natural:

• O espeto está na mesa.

Other orders are possible for emphasis or style, for example:

• Na mesa está o espeto.

That version is grammatical, but it sounds more marked or literary. For everyday speech, stick with:

• O espeto está na mesa.

Espeto usually means skewer or spit.

In Brazil, it is a common word in food contexts, especially barbecue:

• a metal or wooden skewer
• a spit used for roasting meat

So depending on context, espeto might refer to a cooking skewer, a barbecue skewer, or a spit.

Yes, it is a perfectly natural sentence grammatically.

Whether it is common depends on the situation. If people are cooking, setting a table, or talking about barbecue tools, O espeto está na mesa is completely plausible.

It is a simple, natural example of:

• a definite article
• estar for location
• em + a = na