You're really means ‘you are’, the apostrophe (apostrophe = ') shows us that the ‘a’ is missing:
"You're really boring. I wish I didn’t have to sit next to you all day.”
Your is a possessive pronoun and should be followed by a noun:
‘Your car, your phone…’
One common mistake is to say, ‘Hope your okay’.
It should, of course, be, ‘Hope you're okay’.
Have you got it? Then, try these...only use your or you're