Scripting languages like Python usually allows for fairly fast developement - because many of them are in higher levels that doesn't require you to manage the annoying low level bits all the time. e.g. like creating array to a certain size, and if you blow through that size, you'll have to reallocate space, same for buffers, and stuff. With some scriptinglanguage, there are no differentiation between types (you don't have to say that the variable stores an integer, or a floating point number, or others). Also, usually scripting language tries to be programmer friendly - it is fairly easy to learn, and things are easy enough to read that even a non-programmer can kinda follow what is going on.
Probably makes a decent languages to build mods without writing your own scripting language.
But problem with most scripting language is that they don't paticularly compile the code into the machine code that your CPU understands. They usually do this on-demand. So the python interpreter (a program that is compiled to machine code) reads the script, and convert the script to machine code, and then that machine code gets executed (I'm sure I'm missing something here, or I might even be wrong). While compiled languages like C/C++ takes a program that reads the source file, and converts it into machine code that the CPU understands, and you're given this code to execute.
There are advances that makes [semi-]interpreted languages run faster. I think my compiler prof said that the latest Java may figure that certain piece of code gets executed a lot, and it would optimize and compile that section into machine code.