can anyone explain me the negative interest rates of japan? does it mean you cant keep money in a bank account? or is it something else?

Negative interest rates disincentivizes holding cash by making money practically free. Banks are penalized for parking money in the BoJ so they just lend to whomever.

Zero inflation might look on paper but it a symptom of stagnation. In a healthy economy business take out loans to expand or buy equipment. This creates an downstream effect of creating demand. The cost of goods goes up and so does labor. The average worker is more productive with the new equipment and is more valuable. Ideally, this means raises or higher initial wages. More wages means more consooming so money is pumped back into the system.

The """"problem"""" with the Japanese, and Asian cultures in general, is that they prefer to save money for a rainy day rather than just spend it immediately. Stimulus checks turbocharged America but mostly went into savings in Japan

What you should take away here is "hoodrich" minorities are the reason why American consumerism remains strong. Black people spend money as soon as they get it and thus drive inflation. Japan doesn't have as many people with that mindset. Japan must import migrants if it is to survive