Mi prima es muy sociable, pero también es un poco despistada y siempre se deja las llaves en casa.

Because mi is a possessive adjective, and it goes directly before the noun:

• mi prima = my cousin

Mía is a possessive pronoun/adjective used differently, usually after the noun or on its own:

• una prima mía = a cousin of mine
• Es mía = It’s mine

So before a noun, you normally use mi, not mía.

Spanish usually uses ser for more permanent or characteristic qualities, and estar for temporary states or conditions.

Here, sociable and despistada are being presented as personality traits, so es is the natural choice:

• Es muy sociable
• Es un poco despistada

If you used está, it would sound more like a temporary state, which doesn’t fit as well here.

It’s repeated because Spanish often repeats the verb in this kind of structure for clarity and rhythm:

• Mi prima es muy sociable, pero también es un poco despistada

You could sometimes hear a reduced version in speech, but repeating es sounds natural and standard. It helps separate the two descriptions clearly:

• She is very sociable, but she is also a little absent-minded

También means also or too.

In this sentence, it adds a second characteristic:

• pero también es un poco despistada = but she’s also a little absent-minded

So the sentence is balancing two ideas:

• one positive trait: muy sociable
• another trait: un poco despistada

Because un poco is a fixed expression meaning a little.

Here, poco is not acting like a normal adjective agreeing with prima. It’s part of the adverbial phrase un poco, which modifies despistada:

• un poco despistada = a little absent-minded

So it stays un poco, no matter whether the person is masculine or feminine:

• un poco cansado
• un poco cansada

Despistada means something like:

• absent-minded
• scatterbrained
• forgetful
• easily distracted

It comes from despistado/despistada, which agrees with the person being described. Since prima is feminine, it becomes despistada.

It often suggests someone who forgets things, misses details, or gets distracted easily.

Because adjectives in Spanish usually agree in gender and number with the noun they describe.

• prima is feminine singular
• so the adjective must also be feminine singular: despistada

Compare:

• Mi primo es despistado
• Mi prima es despistada

Here, dejarse means to leave something behind or to forget something somewhere.

So:

• se deja las llaves en casa means she leaves her keys behind at home

This is a very natural Spanish way to express accidentally forgetting something somewhere.

It’s slightly different from just deja, because dejarse algo is a common idiomatic pattern for forgetting/ leaving something behind unintentionally.

The se is part of the pronominal verb expression dejarse algo.

In this construction, it often suggests that the person accidentally leaves something behind:

• Me dejé el móvil en casa = I left my phone at home
• Se deja las llaves en casa = She leaves her keys at home / forgets her keys at home

You should think of dejarse algo as a set expression, rather than trying to translate se word for word.

Spanish often uses the definite article instead of a possessive when it’s already obvious who the object belongs to.

So instead of saying her keys, Spanish naturally says the keys:

• se deja las llaves en casa

Because we already know we’re talking about my cousin, it’s understood that the keys are hers.

Using sus llaves is possible, but here las llaves sounds more natural.

Because in Spanish, as in English, keys are often referred to as a set.

• la llave = the key
• las llaves = the keys

In everyday life, people usually mean their house keys, keyring, or set of keys, so the plural is very common.

En casa is the usual idiomatic way to say at home or home.

• Estoy en casa = I’m at home
• Se deja las llaves en casa = She leaves her keys at home

If you say en la casa, it sounds more like you are referring to a specific house as a building:

• en la casa de Ana = in Ana’s house

So en casa is the natural choice when you mean at home in a general sense.

Because Spanish adverbs like siempre often go before the verb phrase:

• siempre se deja las llaves en casa

This is a very natural word order and means she always leaves her keys at home.

You may hear slight variations in word order for emphasis, but this placement is standard and common.

Yes, you could, and it would be understandable. But se deja las llaves en casa sounds especially natural for leaving something behind.

There is a small nuance:

• olvida las llaves focuses on forgetting
• se deja las llaves focuses on leaving them behind

In many situations, both work, but dejarse algo is very idiomatic in Spanish for this kind of mistake.

Not necessarily. The present tense in Spanish is often used for habitual actions too.

So here:

• siempre se deja las llaves en casa

means this is something she regularly does, not just something happening at this exact moment.

The word siempre makes that habitual meaning especially clear.

Yes. They both show degree, but at different levels:

• muy sociable = very sociable
• un poco despistada = a little absent-minded

So they both modify adjectives, but:

• muy increases the intensity a lot
• un poco softens it

This combination is very common in Spanish when describing people.

Yes. It shows several very common patterns:

• ser + adjective for personality: es muy sociable
• adding contrast with pero: pero
• adding another trait with también: también es
• softening a description with un poco: un poco despistada
• describing a habitual action with the present tense: siempre se deja...

So it’s a very natural everyday sentence for talking about someone’s character and habits.