Lesson Nine (Leciono Naux): Direct and Indirect Objects
Esperanto typically uses subject-verb-object as the word order in simple declarative statememts. A sentence can be a simple subject-verb (e.g., Mi mangxis, "I ate"), where subject is the noun which performs the action, or it can be elaborated to indicate the direct object that the verb is performed on (e.g., Mi mangxis fisxon, "I ate fish").
Note that the direct object of a phrase can be identified by adding "n" (e.g., fisxo, "fish", fisxon, "fish" as a direct object). La kato amas la ratojn is "The cat loves the rats". However the word order can be change to object-verb-subject, but with the direct object still indicated (e.g., La ratojn amas la kato = The rats are loved by the cat). Note that in the plural form the -n affix to indicate the direct object occurs after the -j affix to indicate a plural.
This flexibility continues into indirect objects. Indirect objects are nouns which are neither performing an action (the subject) nor having an action performed on it (the direct object), but rather the indirect receiptient of the verbal action. Consider the sentence, La kelnero donas fiŝon al la virino, "The waiter [subject] gives [verb] fish [direct object] to the woman [indirect object]".
In Esperanto, the indirect object will always take a preposition, regardless of word order. Indeed, in Esperato, as long as the direct object is identified by a concluding -n and the indirect object by a preposition, subject, verbs, direct objects and indirect objects can be in any order. English can do this, but with some fairly archiac locutionary gynmanstics.
La kelnero donas fiŝon al la virino, "The waiter [subject] gives [verb] fish [direct object] to the woman [indirect object]".
Fiŝon al la virino la kelnero donas, "Fish to the woman the waiter gives"
Al la virino la kelnero donas fiŝon, "To the woman the waiter gives fish"