Actually, it is pretty specific. In essence, Buffett says you should first figure out what it would be worth to own the entire company (the "intrinsic value"; calculating this is something of a black art) then divide that by the number of shares the company has issued. Only if the current price per share is significantly lower than that (the "margin of safety") should you think about buying.
Which is about as specific as "First you should figure out what it is that cures cancer, and then you should have people with cancer do that thing." Calculating the intrinsic value of a business is very, very difficult -- which is why Buffett is so rich from being good at it.
