Re: Is it true that Banks wont open in Bank Holiday?

In the UK, a "bank holiday" is a public holiday. Most businesses, except for some shops, are closed. Banks are also closed -- and presumably this was the original reason why it was called a "bank holiday" -- but nowadays there is not a very strong association in most people's minds between banks and bank holidays. If you're translating from English to another language there's no need to mention anything about banks. Just translate it as "public holiday".

It is not natural to say that someone is "on Bank Holiday".