"The one who lives above the bank is playing among the trams and taxis."
Translation:Az játszik a villamosok és a taxik között, aki a bank fölött lakik.
Az........., aki........... Does it really fit together in one sentence? Aki is only for persons, but az (that)? I need help please, to understand that.
Normally it's not polite to refer to people with "az", but this structure is fixed, there's nothing you can substitute "az" with.
Yes, this is perfectly normal, this is how you have to do it. Occasionally you can enhance it like this:
"Az az ember......., aki ......".
But it is optional. And the "az" is still there.