1. To move in an energetic, uncontrolled way when you are in water in order to try not to sink. English = flounder, thrash about.
2. To not know what to say or do in a situation; to not know what to do to protect or save yourself. English = flounder, (be) helpless. Idiomatic English = (be) all at sea.
3. To be confused, disordered or extremely anxious; to be greatly confused and disordered. English = (be) in turmoil; (be) chaotic.
4. To move or handle things in a careless, awkward way, often so that things are knocked over or broken. English = (be) clumsy, (be) awkward, (be) stilted.