In Russian, we use special words called prepositions. These words help us understand the action in a sentence. They can change how nouns behave depending on the preposition used. Two important types of cases to know are the accusative case and the instrumental case.

Accusative Case

The accusative case helps us find the direct object of a verb. It tells us what is being affected by the action. This case often shows movement toward a place or a goal. Here are some key prepositions that go with the accusative case:

• в (in) – This means you are moving into a place.
  • Я еду в Москву. (I am going to Moscow.)
• на (on) – This shows you are moving toward a surface.
  • Мы идём на рынок. (We are going to the market.)

Instrumental Case

The instrumental case explains how an action is done or what something is done with. It can also show companionship. Here are some important prepositions for the instrumental case:

• с (with) – This shows that you are together with someone or how you do something.
  • Я говорю с другом. (I am talking with a friend.)
• по (along/by) – This is used for actions that use a means.
  • Мы путешествуем по России. (We are traveling across Russia.)

By understanding these cases, it's easier to see how sentences are built and how nouns work with the prepositions in front of them.