Q-1
That line tells the program that the variable "EneObj" holds a value of "11". Variables are really useful and one of the first things you should learn about. In the case of that particular variable, i would assume it is the object number of an enemy object. Each object has an individual index number, that only it can have. If two objects have the same number, DB will give an error and quit. The reason for using a variable to hold an object number, is that it improves read-ability of your code.
Position Object EnemyObject,X,Y,Z
is much easier to understand than
as you know which object you are referring to, rather than just a number.
Q-2
For ene=EneObj to EneObj+4
That ^ is the start of a "For - Next Loop" Its explained in the help files but it basically means that the variable ene is looped through the values of EneObj to EneObj+4. "For - Next Loops" are incredibly useful, so make sure you learn them.
Q-3
In dark basic, it doesn't matter wether you use capital letters or not, as code will work regardless. But it does make it easier to read, which is important.
ThisVariableStoresANumber = 5
is much easier to read than
thisvariablestoresanumber = 5
Hope that helped.