Mi prima abre el atlas cuando duda en qué continente está ese país.

In Spanish, prima means female cousin, and primo means male cousin. It does not specifically mean first cousin only; in normal use, it usually just means cousin unless extra detail is added.

So:

• mi prima = my female cousin
• mi primo = my male cousin

Spanish often makes the cousin’s gender explicit in a way English usually does not.

In standard modern Spanish, possessives like mi, tu, su, nuestro normally go without an article before the noun.

So you say:

• mi prima
• tu casa
• su país

Not:

• la mi prima ❌

Older Spanish and some regional/literary styles may use article + possessive, but that is not the normal modern pattern.

Spanish often leaves out subject pronouns because the verb ending already shows who the subject is.

• abre = she opens / he opens / you open (formal)
• duda = she doubts / is unsure

Since mi prima is already stated, adding ella would usually be unnecessary.

So:

• Mi prima abre el atlas... = perfectly natural
• Mi prima ella abre el atlas... = usually unnatural here

Spanish is a pro-drop language, so omitted subject pronouns are very common.

Abre is the third-person singular present indicative form of abrir.

Conjugation of abrir in the present:

• yo abro
• tú abres
• él/ella/usted abre
• nosotros abrimos
• vosotros abrís
• ellos/ellas/ustedes abren

Here, the subject is mi prima, which is third-person singular, so abre is the correct form.

Using el here suggests a specific atlas, or the atlas she normally uses.

• abre el atlas = she opens the atlas
• abre un atlas = she opens an atlas

Both are grammatically possible, but they mean slightly different things. El sounds more natural if we imagine a known, specific atlas.

Because grammatical gender in Spanish is not determined only by the ending. While many words ending in -a are feminine, there are exceptions.

Atlas is masculine:

• el atlas

Other masculine exceptions include:

• el día
• el mapa
• el problema

So this is just something to learn with the noun: el atlas.

Because this sentence describes a habitual or repeated action in the present.

• cuando duda = when she is unsure / whenever she is unsure

The indicative is used after cuando when talking about something habitual, general, or real.

By contrast, the subjunctive is used after cuando for a future or not-yet-real situation:

• Cuando dude, abrirá el atlas. = When she is unsure, she will open the atlas.

So in your sentence, cuando duda means this is something she does regularly.

Literally, dudar means to doubt, but in many contexts it is more natural in English to translate it as:

• to be unsure
• to wonder
• to not be certain

So here:

• cuando duda en qué continente está ese país

is more naturally understood as:

• when she is unsure which continent that country is in

A very literal translation like when she doubts in which continent that country is would sound unnatural in English.

Because qué with an accent is used in questions and indirect questions.

Here, en qué continente está ese país is an indirect question:

• which continent is that country in?

So it needs the accented form:

• qué

Compare:

• No sé qué quiere. = I don’t know what he wants.
• El libro que quiero... = The book that I want...

In the second example, que has no accent because it is a relative pronoun, not a question word.

The en belongs to the idea of being in a continent:

• Ese país está en Europa.
• Está en África.

So when that becomes a question, the preposition stays:

• ¿En qué continente está ese país?

And in the sentence, that same structure is embedded as an indirect question:

• duda en qué continente está ese país

So the en is there because Spanish says a country is in a continent.

Because Spanish keeps the normal question-word-first order in both direct and indirect questions.

Direct question:

• ¿En qué continente está ese país?

Indirect question:

• No sé en qué continente está ese país.
• Duda en qué continente está ese país.

If you say ese país está en qué continente, it sounds wrong as a standard question structure.

So Spanish usually places the question phrase first:

• en qué continente

followed by the verb:

• está

and then the subject:

• ese país

Because the sentence is talking about location, and location is normally expressed with estar, not ser.

• ese país está en Europa = that country is in Europe

Use estar for where something is located.

By contrast, ser would be used for identity or classification:

• Es un país europeo. = It is a European country.

So here, since the question is about where the country is located, está is the correct verb.

Ese país means that country, so it points to a specific country that is somehow already known in the conversation or context.

• el país = the country
• ese país = that country

Using ese adds a demonstrative idea: the speaker is referring to a particular country, not just any country.

In standard Spanish, both are demonstratives, but they differ in distance or perspective.

• este = this
• ese = that
• aquel = that over there / that more distant one

So:

• ese país = that country
• aquel país = that country over there / that more distant country

In modern everyday Spanish, especially outside very clear distance contrasts, ese is often used more broadly, and aquel can sound more literary or more specifically distant.

Yes, that is possible, but it is a slightly different structure.

• ¿En qué continente está ese país? = Which continent is that country in?
• ¿De qué continente es ese país? = more like What continent does that country belong to?

Both can work in many contexts, but estar en focuses on location, while ser de can sound more like origin, belonging, or classification depending on context.

In your sentence, en qué continente está is a very natural way to express the idea.

It can appear in several patterns.

Common ones include:

• dudar de algo = to doubt something
  • Dudo de su historia.
• dudar si... = to be unsure whether...
  • Dudo si ir.
• dudar + indirect question
  • Duda qué hacer.
  • Duda en qué continente está ese país.

In your sentence, duda introduces an indirect question: which continent that country is in.

It most naturally sounds like a habitual action:

• My cousin opens the atlas whenever she is unsure which continent that country is in.

The use of the present tense plus cuando often gives that repeated, general meaning.

If you wanted to make it clearly about one specific past event, Spanish would change the tense:

• Mi prima abrió el atlas cuando dudó en qué continente estaba ese país.

Yes, grammatically you could say:

• Mi prima abre el mapa...

But the meaning changes slightly.

• atlas = an atlas, usually a book of maps
• mapa = a map

So abre el atlas suggests she opens a book or collection of maps, which fits especially well with checking continents.