If you format the code properly then it is much easier to see what is going on
int count = 0;
void setup()
{
Serial.begin(9600);
}
void loop()
{
if (count == 3)
{
Serial.println(count);
}
count++;
}
count is incremented each time through loop() whether or not the if returns true and the value of count is printed. The for loop will run very quickly, so count will be incremented very quickly until its value rolls over to zero and it starts counting up again as explained in reply #2