A direct object of the sentence is marked by را, which immediately follows the noun. Technically this case is the same as accusative, as opposed to dative, the indirect objective case:

آن کتاب را دیدم
ān ketab rā didam
“I saw that book.”

If there are attributive adjectives regarding the noun, then را comes after the cluster of the noun plus its adjective:

.آن کتاب فارسی را دیدم
ān ketab-e fārsi rā didam
“I saw that Farsi book.”

.آن کتاب خوب را دیدم
ān ketab-e xub rā didam
“I saw that good book.”

If there is any extra elaboration for the noun as the object of the sentence, that elaboration comes after the را:

.آن کتاب فارسی را که می گفتی خریدم
ān ketab-e fārsi rā ke migofti xaridam
“I bought the Persian book that you said.”

While both in English and Persian an indirect object (dative) takes one of many prepositions
(to me به من, from there ازآنجا, etc.), English does not have a marker for the direct object. Instead, when an object does not take any prepositions, it is a direct object, as in he hit me. In addition, if there are two objects in the sentence, in English usually the first one is indirect and the second one direct, as in she gave me the book. In some cases, however, it may also follow it, as in she gave the book to me.

In Persian, if there are two objects, usually the first one is direct and the second one is indirect:

.آن کتاب را به او دادم
ān ketab rā be u dādam
“I gave him/her that book.”

.پسرم را به مدرسه بردم
pesaram rā be madrese bordam
“I took my son to school.”