Here, a means the, not a/an.
In Portuguese, a can be:
In A carta está na mesa, a carta means the letter.
If you wanted a letter, you would say uma carta.
The preposition em is broader than English in. Depending on context, it can correspond to:
So na mesa is literally based on em, but with mesa the natural English translation is usually on the table.
Portuguese does not always separate in and on the same way English does.
The accent mark shows the stressed syllable and helps distinguish the correct written form.
That acute accent is important in standard spelling.
A simple approximate pronunciation for an English speaker is:
A few notes for Brazilian Portuguese:
A more natural connected rhythm may sound closer to:
Portuguese uses definite articles more often than English does.
So na mesa = on the table is the normal form.
Saying em mesa would usually sound wrong in this context. Portuguese generally wants the article here because you are talking about a specific table.
Yes. Sobre a mesa also means on the table.
In many situations, both are fine.
This is the normal, neutral word order:
Portuguese can change word order for emphasis, but this standard order is what learners should use first.
For example:
Usually, yes, carta commonly means a letter, especially a written letter.
But depending on context, carta can also mean things like:
In A carta está na mesa, the most natural meaning is a physical letter.
The article and the contraction would change.
For a masculine noun, you would often get:
Example:
In your sentence:
So feminine grammar appears twice in the sentence.
The base form is estar, meaning to be.
Está is the third-person singular form in the present tense, used with:
So:
Yes, in a broad sense. Using estar suggests the letter is currently located there.
That does not necessarily mean it will move soon, but it presents location as a state or position, not as an essential characteristic.
That is why estar is the normal verb for where something is: