"Where do you have to go?"
Translation:तुम्हें कहाँ जाना है?
There are 3 ways to say YOU in Hindi. आप, तुम and तू।
आप is the politest (used with elders or people you meet for the first time etc) But yes, if they allow you to use तू or तुम then it's their personal preference....
I wouldn't consider तू as the rudest, it surely is not. It can be thought of as the most 'frankest' (used with people close to you like your friends or younger people)
NOTE: Avoid using तू with your parents and older relatives, you might sound rude in that case (even if they're close to you, they are still your elders) and also if you meet a person younger than you for the first time, dont use it (it's your first time meeting them so suddenly using the 'frankest one' sounds obviously rude)
Then comes तुम. It is somewhat between आप and तुम। You can use this with anyone, even the people you meet for the first time. Just about anyone, except elders.
Elders are ALWAYS to be reffered with आप.
Hope this helps you as well as others.... Good Luck learning Hindi!!!