"What is the bank like?"
Translation:Milyen a bank?
Because it doesn't make sense in Hungarian. You don't need 'van' to say WHAT something is in the third person singular - or 'vannak' in the third person plural. But you would need it if you were talking about LOCATION, eg 'Hol van a bank?' = where is the bank. Moreover, you need 'milyen', not 'mi', to say what something is like, and furthermore it is nominative case, 'milyen', not accusative case 'milyenet' or, as you have put it, 'mit'.