Translation:Which one is it?
In addition to B_bethany's explanation, I would mention that どちら is more polite than どっち. どちら would actually be considered the regular form. Unless you are on familiar terms with the other party and they speak casually with you, it is probably best to stick to どちら until you're more comfortable.
どちら can also mean 'who', as in 'Who are you' / 'Who is calling?' どちら様（さま）でしょうか？
Use of question words どれ and どっち indicates that the answer is limited just a couple or a few choices. It is best to translate it within such parameters. C.
Conversationally, it might be acceptable (given proper context).
For example, someone performing a shell game might use 'Where is it?' to mean 'Which one (of the cups) is it in?'.
'Which direction is it?' / 'Which way is it?' could reasonably be argued to be correct translations, but 'Where is it?' is a bit too broad.