This is the 278th most frequent Russian word.
алексей
"Алексей" is a Russian male given name, equivalent to "Alexei" in English.
In this sentence, "Алексей" is a proper noun serving as the subject of the sentence, indicating the person who is performing the action.
Алексей читает интересную книгу.
Alexei is reading an interesting book.
In this sentence, "Алексею" is in the dative case, showing that he is the recipient of the gift.
Друзья подарили книге Алексею.
Friends gave a book to Alexei as a gift.
Here, "Алексей" is used as the object of the verb within the sentence, indicating the individual observed by the subject in the action.