O rádio está na mesa.

In Portuguese, it is very common to use the definite article with nouns, especially when talking about a specific thing.

• o rádio = the radio
• rádio on its own can sometimes appear, but o rádio is the normal choice here.

So O rádio está na mesa sounds natural in the same way The radio is on the table does in English.

Rádio is a masculine noun in Portuguese, so it takes the masculine article o:

• o rádio = the radio

This is something you usually just have to learn with the noun. The ending -o often suggests a masculine noun, and in this case that matches.

The accent in rádio shows where the stress goes:

• rá-di-o

The stress is on the first syllable: RÁdio.

Without the accent, a learner might guess the wrong pronunciation. In Portuguese, accent marks are important because they often tell you how to stress the word.

Portuguese has two common verbs for to be: ser and estar.

Here, está is used because it expresses location:

• O rádio está na mesa. = The radio is on the table.

A simple rule that helps:

• ser = identity, permanent characteristics, definitions
• estar = location, condition, temporary states

So for where something is, Portuguese normally uses estar, not ser.

Está is the third-person singular form of estar in the present tense.

Conjugation:

• eu estou = I am
• você/ele/ela está = you/he/she is

Since o rádio is singular, the verb must also be singular:

• O rádio está...

Na is a contraction of:

• em = in / on / at
• a = the (feminine singular)

So:

• em + a = na

That means:

• na mesa = on the table / in the table / at the table, depending on context

In this sentence, the natural English translation is on the table.

Because mesa is a feminine noun:

• a mesa = the table

Since na comes from em + a, it must match the feminine noun:

• na mesa

If the noun were masculine, you would use no:

• no carro = in the car
• no quarto = in the bedroom

Yes, often it does. Portuguese em is broader than English in.

Depending on context, em can correspond to:

• in
• on
• at

So:

• na mesa can literally come from in the table, but in normal English we say on the table

This is one of those places where Portuguese and English divide space differently.

Yes, but O rádio está na mesa is the most neutral and natural order.

This is the basic pattern:

• subject + verb + place
• O rádio
  • está
    • na mesa

You could change the order for emphasis, for example:

• Na mesa está o rádio.

But that sounds more marked or literary. For everyday speech, O rádio está na mesa is best.

A helpful approximate pronunciation is:

• oo HAH-dyoo es-TAH nah MEH-zah

A few notes:

• o sounds like oo here
• rádio has stress on RÁ
• está has stress on the last syllable: tá
• mesa sounds like MEH-zah
• in Brazilian Portuguese, the s in mesa sounds like z

Yes, absolutely. It is a completely normal and natural sentence.

A Brazilian might also say similar sentences like:

• O celular está na mesa. = The cellphone is on the table.
• O livro está na mesa. = The book is on the table.

So this sentence is a good model for talking about where things are.

Yes. Rádio can refer to:

• the physical device: the radio
• radio as a broadcast medium: radio

Examples:

• O rádio está na mesa. = The radio set is on the table.
• Eu escuto rádio todo dia. = I listen to radio every day.

Context usually makes the meaning clear.