The first software solution is quite simple and initiates a delay and then rereads the state. The time between the two input reads is defined by a delay. If the delay is too short, the switch may be still bounding.

int switchPIN = 7;           // pin switch
int switchStatus;            // status switch
int switchStatusLast = LOW;  // last status switch
int LEDpin = 4;              // pin LED
int LEDStatus = LOW;         // current status LED

void setup() {
Serial.begin(9600);
pinMode(LEDpin, OUTPUT);  // LED pin as output
}

void loop() {
switchStatus = digitalRead(switchPIN);   // read status of switch
if (switchStatus != switchStatusLast)  // if status of button has changed
    {
      delay(50);     // debounce time of 50 ms
      switchStatus = digitalRead(switchPIN);   // read the status of the switchPIN again
      if (switchStatus != switchStatusLast) // if the status of the button has changed again
      {
        // if switch is pressed than change the LED status
        if (switchStatus == HIGH && switchStatusLast == LOW) LEDStatus = ! LEDStatus;
        digitalWrite(LEDpin, LEDStatus);  // turn the LED on or off
        switchStatus = switchStatusLast;
      }
    }
}

You see in the following pictures of the oscilloscope that the press and release voltage is more smoothly than without a software solution. This results in the behavior that when the button is pressed once, the LED turns on or off. The following video also shows the result of the software solution against debouncing.