How do you say the one in Russian?

The word for "one" in Russian is один (pronounced "ah-deen").

It's important to note that "один" is masculine. If you're talking about something feminine, you would use одна (pronounced "ahd-nah"). If you're talking about something neuter, you would use одно (pronounced "ahd-no").

For example:

* Один мальчик (One boy)

* Одна девочка (One girl)

* Одно яблоко (One apple)