Well, many products come from China. Ranging from common accessories to computers and cell phones. Add industrial machinery and raw materials to that. Bangladesh is a small and densely populated country.
Also, you forgot the fact that China is the largest supplier of military equipment to Bangladesh. So yes, the trade balance is pretty high.
Even India has a high trade imbalance with China. No biggy, but a concern
The US:
Bangladesh has a long way to go balancing its trade gap with India:
Trade gap with China would be there for obvious reasons. And they are interested in free trade as well, along with better inter-nation connections. But that'll take time.