Formal:
* Я знаю несколько слов. (Ya znayu neskol'ko slov.) - This is the most literal and formal way to say it.
* Я владею несколькими словами. (Ya vladeyu neskol'kimi slovami.) - This is more formal and emphasizes the ability to use those words.
Informal:
* Я знаю пару слов. (Ya znayu paru slov.) - This is more informal and means "I know a couple of words".
* Я немного знаю русский язык. (Ya nemnogo znayu russkiy yazyk.) - This is a more general way to say "I know a little bit of Russian".
Other options:
* У меня есть небольшой словарный запас. (U menya est' nebol'shoy slovarnyy zapas.) - This means "I have a small vocabulary".
* Я могу сказать несколько фраз. (Ya mogu skazat' neskol'ko fraz.) - This means "I can say a few phrases".
The best option for you will depend on the context of the conversation.