Mi amiga llegó asustada.

Because they refer to a female person.

• amiga = female friend
• asustada = frightened/scared, describing a female person

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

So:

• Mi amiga llegó asustada. = My female friend arrived scared.
• Mi amigo llegó asustado. = My male friend arrived scared.

If it were plural:

• Mis amigas llegaron asustadas.

Llegó is the preterite form of llegar for él/ella/usted.

Here it means she arrived.

The preterite is used because arrival is seen as a completed event:

• Mi amiga llegó asustada. = My friend arrived scared.

This focuses on the fact that she arrived, as a finished action.

Compare:

• llegó = she arrived
• llegaba = she was arriving / used to arrive

So llegó is the natural choice here because the sentence is about a single completed arrival.

It is an adjective, not an adverb.

It describes the state of the subject (mi amiga) at the moment she arrived.

So the structure is:

• Mi amiga = subject
• llegó = verb
• asustada = adjective describing how she was when she arrived

English often uses something similar:

• She arrived tired.
• He came angry.

In grammar terms, this is often called a predicative adjective or a depictive adjective: it describes the subject during the action.

Because the sentence is not just saying what her emotional state was. It is saying how she was when she arrived.

• Mi amiga llegó asustada. = She arrived scared.
• Mi amiga estaba asustada. = She was scared.

The first sentence combines:

1. the action of arriving, and
2. her condition at that moment.

If you say:

• Mi amiga estaba asustada cuando llegó.

that means:

• My friend was scared when she arrived.

That is also correct, but it is a slightly different structure and feels more explicit.

It mainly means that at the moment of arrival, she was scared.

It does not clearly say when the fear started.

So it could mean either:

• she was already scared before she arrived, or
• she ended up scared by the time she arrived

The sentence focuses on her state upon arrival, not the exact beginning of that state.

If you want to be more specific, Spanish can do that:

• Llegó ya asustada. = She arrived already scared.
• Se asustó al llegar. = She got scared upon arriving.

Asustada usually means scared, frightened, or startled.

The exact translation depends on context.

It comes from the verb asustar = to frighten / to scare.

So:

• estar asustado/a = to be scared
• asustarse = to get scared

In this sentence, asustada describes her emotional condition, so scared or frightened are the most natural translations.

The accent mark shows both pronunciation and meaning.

• llegó = she/he/it arrived
• llego = I arrive (present tense)

So the accent helps distinguish the forms.

Pronunciation:

• llegó has the stress on the last syllable: lle-GÓ
• llego has the stress on the first syllable: LLE-go

That written accent is very important.

Yes, absolutely.

That means:

• My friend arrived very scared.

Adding muy intensifies the adjective.

Other natural variations are:

• Mi amiga llegó bastante asustada. = fairly/quite scared
• Mi amiga llegó un poco asustada. = a little scared

So asustada works very naturally with degree words like muy, bastante, and un poco.

If you want to say my friend, then mi is necessary.

• Mi amiga = my friend
• La amiga = the friend
• Una amiga = a friend

Spanish often drops subject pronouns like yo, tú, ella, but it does not normally drop possessives like mi when they carry essential meaning.

So:

• Mi amiga llegó asustada. = My friend arrived scared.
• Amiga llegó asustada. is not correct in normal Spanish.

Yes, but the basic order here is the most natural:

• Mi amiga llegó asustada.

Spanish does allow some flexibility for emphasis or style, but not every change sounds equally natural.

For example:

• Asustada, mi amiga llegó. = possible, more literary or emphatic
• Mi amiga asustada llegó. = less natural in this meaning; it can sound like my scared friend arrived, treating asustada more as part of the noun phrase
• Llegó asustada mi amiga. = possible in some contexts, but marked or poetic

For everyday Spanish, Mi amiga llegó asustada is the best standard version.

The adjective and sometimes the noun change to match gender and number.

• Mi amigo llegó asustado. = My male friend arrived scared.
• Mis amigas llegaron asustadas. = My female friends arrived scared.
• Mis amigos llegaron asustados. = My male friends / my friends arrived scared.

Notice the agreement:

• singular feminine: asustada
• singular masculine: asustado
• plural feminine: asustadas
• plural masculine: asustados

And the verb changes too:

• llegó = singular
• llegaron = plural