You have an array...
int x[] = {}; // empty array
you make a random number between 50 and 200
long y = random(50, 200);
you run a loop to then fill that array with a random number where the loop is 50 to 200 numbers
for(int c=0; c<=y-50; c++){
x[c] = random(1, 10);// stick a random number in it 1 to 10
}
When I run that in the Arduino to verify it, I get no errors.
Happy?