It depends on the person who wrote the tab. There's no real standard format for tabs (hence the reason we also include the sheet music)
v might stand for strum downwards and /r might stand for slide up and release.... but unless the person who wrote the tab explains it or there's an audio example to learn from, it's just a guessing game.

If it's one of our instructors, best thing to do is write them and ask for verification or post a link to the lesson and one of us can probably figure it out for you.