" What floats your boat" means what the words suggest. It means, whatever is necessary, whatever you need,. In the phrase it could be a lake, a tide in the sea, or a flood.
You are studying English by classes, Italki, talking to people, reading and podcasts. Whatever floats your boat.
I.e. whatever it takes to get you there (to English proficiency), whatever it takes to 'float a boat'.
English is a colourful language.