Why is the sentence "A la niña le gustan los caballos" structured as it is?
 

I'm still a beginner and am having a bit of trouble understanding this sentence: "A la niña le gustan los caballos".


I know it means "The girl likes the horses", but I'm a bit confused on how it's formed. I'm unclear why the personal "a" is used at the beginning, why the indirect object "le" meaning "to her" is used, and why "gustan" is used instead of "gusta".



Is this supposed to be like the passive voice in English? So it may be closer to "The horses are liked by the girl"? That would explain the plural verb matching the plural subject "horses", and possibly the "le" being "by the girl" or "to the girl". But I'm still unsure.

The most common ways to translate "a la niña le gustan los caballos" is "the girl likes the horses" or "the girl likes horses". However, the grammar of the Spanish sentence is similar to the English sentence "(The) horses please the girl". The general expression in Spanish is "gustarle algo a alguien" = "someone likes something" OR "something pleases someone". "Algo" = "something" is the subject of "gustar", and "le ... a alguien" = "someone" is the indirect object of "gustar".

In your sentence, the verb "gustan" agrees in person and number with its subject, which is "los caballos". The indirect object is "a la niña", echoed by the indirect object pronoun "le". In general, "gustar" requires using an indirect object pronoun, even if the sentence includes an explicit indirect object such as "a la niña".

The order of elements in your sentence is probably the most commonly used order: "a alguien le gusta algo": that is, indirect object, then indirect object pronoun, then the conjugated form of "gustar", and finally the subject.

Adding to what wrholt said, the elements of the sentence, the parts of speech, can almost appear in any order. Only the indirect object pronoun 'le' must appear before the verb. The other parts of the speech, the subject and the indirect object, if used, can appear before the verb or after the verb and in either order.

What is the direct object in the English equivalent ((the) horses) becomes the subject in Spanish. The indirect object is easy to see if you include the preposition, as shown below. The indirect object pronoun is mandatory, and is, for all intents and purposes, redundant.
(The) horses are pleasing to the girl.