Yes, "life hacks" means that someone has developed skills in dealing with their life (for example, by being able to multi-task or get more organized) in the same way that a hacker is skilled at manipulating a computer system. "What the hack" is never said, as far as I know—"what the heck" is correct (and yes, this is a way to say "what the hell" without using the word "hell").

You've already got two good definitions of 'hack' from Brad C and Nick. And as for 'What the hack', I think you have confused this with 'What the heck'. 'What the heck' was used a milder form of 'What the hell' at a time when people were offended by the inappropriate use of the words with a religious connotation. Nowadays 'heck' is completely inoffensive, and although 'hell' is stronger, it wouldn't upset many people. By the way, neither phrase is 'dirty' : 'dirty words' refer to the body and bodily functions. If you google the phrase 'What the hack!' what you will find is lots of puns, particularly titles of articles and game shows. These is a joke phrase, invented deliberately to catch your eye because it's not quite right. I don't know if the same happens in Chinese, but English-speaking journalists, TV and marketing people love using this kind of word-play to attract people's attention.

1. Hack as many meanings... as you have seen here. 2. dictionaries are very good about explaining polysemy words and homography. For example... http://dictionary.reference.com/browse/hack?s=ts 3. You can think of "life hacks" as a way to mean life skills yes but I would not think of this meaning first. I interpret the meaning of "life hacks" as a way to describe little tricks you can do to improve your life through very simple means. Tricks like getting people to respect you more by using good posture when standing and sitting. This is a life hack. Hope this helps, Nick