I'm new to programming and I've been told that "Javascript is a Turing complete programming language". What is a "Turing complete" P.language?... I've tried to read some articles in Wiki like Turing complete, or Turing completeness but still couldn't get an asnwer that was enough primal and clear to me...
In layman's terms, you can think of it as a "complete" programming language.
In practice, languages which are not Turing complete have somewhat crippling limitations, such as ones which disallow recursion. It may be fine for a limited-purpose language, but it means that some algorithms cannot be expressed, and some others require tortured workarounds.
In computer science, it is an important principle that complex systems can be "reduced" (proven to be isomorphic, i.e. fundamentally equivalent) to very simple systems which we can reason about. It is fairly easy to reason about what a Turing machine (a very crude theoretical abstraction of a modern computer) can and cannot do; we then know that our conclusions must be true for any system which can be reduced to a Turing machine.
But for your concrete question, this is just a snobbish way to tell the snobs you are one of them, actually.