This is a nasty thing to say to somebody. When you tell someone to "get a life", you are telling them, first of all, that they do not already have one. That tells the person that the life that they have has no real value and they should replace their worthless life with something better. I don't know any equivalent. It's not something I ever say.

‘Get a life!’ can have different meanings. Generally it shows disapproval of the actions of the person you’re saying it to, with the suggestion that they stem from having an uninteresting and/or inferior lifestyle. It’s informal. It could mean ‘Mind your own business’ but doesn’t necessarily mean that. There might be other ways to communicate this idea but among native speakers who understand the nuances they will be inferior to the direct ‘Get a life!’

Mind your own business is another way of saying it.