What is the difference between CSS, HTML and JAVASCRIPT ? What can we do by learning all these tgree languages ?

Answer 1

HTML: primarily describes 'what' goes in the web page , specifying the type and structure of the page elements.
CSS : influences 'how' elements are represented, ie style, colour, exact position on screen...
JavaScript: defines dynamic 'behaviour' : how the page reacts to events and user actions, can be used for calculations.

Answer 2

HTML is for putting our website's or Web applications' content in a place.
CSS is for making it beautiful and move our content to a specific pace.
JavaScript is for making it dynamic.

With these 3 you can do Magic!