What role does beginner Nodejs:nodejs play in Web applications?

As the title says, this is my own beginner nodejs (half a day) to Nodejs a few questions, hope to have a can, message answer.

Nodejs Learning Tutorial is not difficult to search, like the Nodejs Chinese web, and W3cschool have related tutorials, looked at a long time, also searched a lot of articles, but there are a few questions, has not been answered:

What role does 1.1:nodejs play in Web applications?

1.2: " If you're a front-end programmer and you don't know a dynamic programming language like PHP, Python or Java, then you want to create your own service, then node. JS is a great choice." "(referred to as W3cschool). Does that mean that nodejs, to a certain extent, can replace wamp to play the role of a Web server?

1.3: If the answer to question 2 is yes, then how does Nodejs deal with the data? For example, PHP operates data through a database in the form of an extension.

1.4: If the answer to question 2 is yes, then how does the Nodejs implement the route? How does its front-end code (HTML) return to the browser to be parsed and displayed? So the problem with the front end is still there? (Example: Different browsers, different versions of compatibility issues)

1.5: If the answer to question 2 is yes, then, what about the Get,post parameter, MVC layering?

What role does beginner Nodejs:nodejs play in Web applications?