"I don't know much Spanish, but I want to speak with you."
It's a polite way of saying you're a beginner in Spanish and would like to practice speaking with someone.
It's a good start to a conversation, but remember, you can make it even more friendly by adding:
* "Could you please speak slowly?" (Puedes hablar despacio, por favor?)
* "I'm learning Spanish." (Estoy aprendiendo español.)
Let me know if you have any other questions! 😊