The program is allocating a dynamic array of integers then using assert to check if the pointer that is pointing to them is not null.
Of course, it isn't - you've just done the assignment in the previous line. If the expression in the assert is false, the program would terminate. In this case it doesn't because it's true as a isn't null.
I'm not sure what you mean by get some of it seen. You're not printing anything to the screen, so you'd need to do that in order for anything to be output. Also, though you've allocated the memory and assigned to the pointer, the array itself contains nothing but junk values. You'd probably want to put something more meaningful in there.
Finally, you have a memory leak. Don't forget that whenever you allocate with new you must always free up with delete unless you make use of smart pointers.
Nothing too catastrophic in this example. The application is short and there's a strong chance that the OS will free up the memory when your program ends. I think an older OS may not have done this, meaning that there'd be system memory that couldn't be accessed after your program has executed.
It's good practice, though and on bigger, more memory-intensive programs it's important to manage your memory.