"Do you like bananas?"
Translation:Ви любите банани?
Ви is grammatically plural. However, you can use it when addressing one person too, to show politeness. But when addressing close friends, it might sound somewhat cold and distant.
Ти is grammatically singular. It's generally impolite to address strangers this way (unless they're small children), but you use it with your friends. However, some friends might prefer «вы», it depends on lots of things.
It's difficult to choose which one to use:
- If you're unsure what to use, choose «ви»! It's better to sound impersonal than to sound rude.
- Just ask. If you have Ukrainian friends or relatives, just ask them what pronouns they prefer. A common scenario is to start using «ви» to a stranger, and then, after being closer to them, ask if they are OK with you using «ти».