Formal:
* আমি বাংলা শিখছি। (Ami bangla shikhchi) - This is the most straightforward and formal way to say it.
* আমি বাংলা ভাষা শিখছি। (Ami bangla bhasha shikhchi) - This emphasizes that you are learning the Bengali language.
Informal:
* আমি বাংলা শিখতেছি। (Ami bangla shikhtechi) - This is a more casual way to say it.
* আমি বাংলা শিখছি। (Ami bangla shikhchi) - This is the same as the formal version, but it can be used in informal situations as well.
* বাংলা শিখছি। (Bangla shikhchi) - This is a very informal way to say it, and it's only appropriate for people you know well.
You could also say something like:
* আমি বাংলা ভাষা শেখার চেষ্টা করছি। (Ami bangla bhasha shekhar chesta karchhi) - "I am trying to learn the Bengali language."
* আমি বাংলা ভাষা শিখতে আগ্রহী। (Ami bangla bhasha shikhte agrehi) - "I am interested in learning the Bengali language."
The best way to say it will depend on the context and your relationship with the person you are speaking to.