In Java what is meaning of public static void ?

Answer 1

I suggest continuing throufh the course, these things are meant to be learned individually, rather than one gulp.
For now just know that's where the program starts.
(What it actually means is what @Empty said)
Though, here's the meaning of the keyword(s):
public means the member is accessible anywhere.
static makes the member bound to the class itself.

Answer 2

public means any package can access that particular method.
static means call that method using the class name and also static keyword is used to store the data in single memory but not the heap one.... in other words, the older data will get overrided by the current data but not separately stored both .
void simply means that particular method will return nothing