It gets put BEFORE the verb of the sentence. It is the subject.  This noun DOES the action of the sentence OR it is what the sentence is ABOUT.

Example: THE FISH saw the bear in the river.

It gets used mainly in prepositional phrases. Translates alone as by/with/in/from. Comes after prepositions like sub, sine, cum.

Example: The fish saw the bear IN THE RIVER.

It gets used mainly in prepositional phrases. Translates alone as by/with/in/from. Comes after prepositions like sub, sine, cum.

Example: The fish saw the bear IN THE RIVER.

It gets put AFTER the verb in the sentence. It is the direct object. The action of the sentence is done to it. It can follow some prepositions (like ante, prope, per)

Example: The fish saw THE BEAR in the river.