Why isn't eu quero uma balcáo correct?
Then you'd have to say "um balcão". It's a masculine word. But it ia not the same as sacada. Sacada is hardly ever counted as balcão, which is used more often as "counter"
The hint for "balcony" doesn't show "sacada". It's been reported.
Couldn't we use varanda as well?
Why is this "quero" and not "quero de"?
The verb querer doesn't require a preposition to introduce a direct object.
as opposed to gostar, precisar.