Mi prima senderista siempre lleva una brújula y un bastón.

Mi without an accent is the possessive adjective meaning my.

• mi prima = my cousin
• mí with an accent is a pronoun meaning me, usually after a preposition:
  • para mí = for me
  • a mí = to me

So here, because it is showing possession, mi is correct.

Yes. In Spanish, prima means female cousin, and primo means male cousin.

So:

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

Unlike English, Spanish often makes this distinction clearly.

Here, senderista is a noun meaning hiker or rambler. It is being used in apposition, meaning it adds extra information about prima:

• mi prima senderista = my cousin, who is a hiker / my hiker cousin

In English, this kind of structure can sound a bit unusual if translated word for word, but in Spanish it is natural.

It can also feel adjective-like in this position, because it describes what kind of cousin she is.

Usually, senderista has the same form for both masculine and feminine. The article or surrounding words show the gender.

• mi prima senderista = my female cousin who is a hiker
• mi primo senderista = my male cousin who is a hiker

This is common with many nouns ending in -ista:

• turista
• periodista
• artista

The word stays the same, but the article or possessive changes.

Siempre means always, and in Spanish it commonly goes before the verb:

• siempre lleva = always carries

This is one of the most natural positions for adverbs of frequency in Spanish.

You may also sometimes hear other placements depending on emphasis, but siempre lleva is the normal, neutral order here.

Llevar is the infinitive form, meaning to carry / to wear / to take.

In the sentence, the verb has to agree with the subject mi prima senderista, which is third person singular, so we use:

• lleva = she carries

Conjugation of llevar in the present tense:

• yo llevo
• tú llevas
• él/ella lleva
• nosotros llevamos
• vosotros lleváis
• ellos/ellas llevan

So lleva is correct because the subject is she.

Here, llevar means to carry.

This verb is very common and has several meanings depending on context, including:

• to carry
• to wear
• to take
• to bring in some situations

In this sentence, because the objects are una brújula and un bastón, the meaning is clearly carries.

Yes, brújula is a feminine noun, so it takes una:

• una brújula = a compass

The ending -a often suggests a feminine noun, and here that pattern works normally.

Brújula has a written accent because of Spanish stress rules.

It is stressed on the first syllable: BRÚ-ju-la.

Without the accent, the normal stress pattern would be different, so the accent mark shows the correct pronunciation.

Bastón usually means stick, walking stick, or cane, depending on context.

In a hiking sentence like this one, it most naturally means a walking stick or hiking stick.

The accent mark in bastón shows that the stress falls on the last syllable: bas-TÓN.

The normal Spanish word for and is y.

So:

• una brújula y un bastón = a compass and a walking stick

Spanish sometimes changes y to e, but only before words beginning with an i sound:

• padre e hijo = father and son

Here the next word is un, so we keep y.

In Spanish, it is normal to repeat the indefinite article with each singular noun when listing separate items:

• una brújula y un bastón

This makes it clear that they are two different objects.

English can sometimes sound similar:

• a compass and a walking stick

So the Spanish structure is very natural here.

Yes, that is a very natural way to understand it in English.

Depending on context, it could be interpreted as:

• my cousin who is a hiker
• my hiker cousin
• my hiking cousin

The exact English wording may change, but the Spanish idea is that the cousin is characterized as a senderista.

Spanish does not always need a separate verb like is when a noun is added directly in apposition.

So instead of saying:

• Mi prima es senderista...

the sentence says:

• Mi prima senderista...

Both are possible, but they are not exactly the same in style.

• Mi prima es senderista = My cousin is a hiker
• Mi prima senderista... = My hiker cousin... / My cousin, who is a hiker,...

The version in your sentence is more compact and descriptive.

Yes, llevar very often means to wear:

• Lleva un sombrero = She is wearing a hat

But here the objects are:

• una brújula
• un bastón

These are things someone would normally carry, not wear, so carries is the natural meaning.

Context tells you which meaning of llevar is intended.