This phrase looks strange because it contains يا which is usually put in front of someone's name when talking to them. This يا however is just part of the phrase. يا ريت has several different translations. It all just depends on the context. It can mean "if only", "hopefully", "I wish", and other meanings that have to do with wishful thinking. In MSA it is pronounced and written as يا ليت (ya leit) and means the same things.
1. يا ريت تعجبكن الصور (ya rayt t'ajibkun assuwar) - Hopefully you guys like the pictures
2. يا ريت كنا نضل صغار (ya rayt kinna ndall izghaar)- If only we had stayed young