It's a polite way to say that you're not fluent in Spanish. You could use this phrase when:
* Introducing yourself: "Hola, me llamo [your name]. No hablo bien español." (Hello, my name is [your name]. I don't speak Spanish well.)
* Apologizing for your Spanish: "Lo siento, no hablo bien español." (I'm sorry, I don't speak Spanish well.)
* Asking for help: "No hablo bien español, ¿puede usted ayudarme?" (I don't speak Spanish well, can you help me?)
It's important to remember that "bien" is a relative term. You could also say:
* "No hablo mucho español" (I don't speak much Spanish)
* "Hablo un poco de español" (I speak a little bit of Spanish)
The choice depends on your level of Spanish proficiency.