Formal:
* আমি বাংলা ভাষা বলতে পারি। (ami bangla bhasha bolte pari) - This translates literally to "I can speak the Bengali language." It's a more formal way of saying it.
Informal:
* আমি বাংলা বলি। (ami bangla boli) - This translates to "I speak Bengali" and is a more casual way of saying it.
You can also use "আমি বাংলা জানি" (ami bangla jani) which means "I know Bengali", implying you can speak it. This is a bit more informal than the formal option but less informal than the second option.
The best way to choose the right phrase depends on who you're talking to and the situation.