Konuşuyorum or Biliyorum?

In Turkish when you want to say that "you speak a language" you do not use the Turkish synonym of the English verb to speak but to know. It is acceptable but the Turkish verb bilmek / to know is more accurate to use in this context.

Let's have a look at these Turkish sentences and their literal English translations.

Ben Türkçe biliyorum. I speak Turkish. 

Ben İngilizce ve biraz (da) Türkçe biliyorum. I speak English and a little Turkish. 

Ben Almanca bilmiyorum. I do not speak German.

Ben Türkçe konuşuyorum. I am speaking Turkish.

This sentence means that at the current moment I am speaking Turkish. 

If you forget and say "konuşuyorum" instead of "biliyorum", you can be sure that everyone will understand that you want to say "you speak". It is not a big mistake at all. But you have a chance to be more impressive :) if you remember and use the more accurate verb which is "bilmek".