Breakdown of Мой брат часто гулял с ним в парке.
брат
brother
парк
park
он
he / it (for a masculine noun) / it (for a neuter noun)
мой
my / mine
Questions & Answers about Мой брат часто гулял с ним в парке.
Why is it с ним instead of с он?
The preposition с (meaning "with") requires the following word to be in the Instrumental case. The word for "he" is он, and its Instrumental form is им. However, when a third-person pronoun starts with a vowel and comes right after a preposition, Russian adds an н- to the beginning of it to make it easier to say. So, им becomes ним.
How would I say "with her" instead of "with him"?
The word for "she" is она, and its Instrumental form is ей. Because it comes after the preposition с, we add the н- to the beginning. "With her" becomes с ней.
Why does the verb гулял end in -л?
The -л ending is the standard past tense marker in Russian. Because the subject of the sentence, брат (brother), is a masculine noun, the verb takes the masculine past tense ending -л. If the subject were feminine, like a sister, it would be гуляла.
Why is there an -е at the end of парке?
This is the Prepositional case, which is used to talk about locations. The dictionary form of the word is парк. When we use the preposition в to say "in the park", we add an -е to the end of regular masculine nouns, making it в парке.