A lot of people cannot bend down to tie their shoes. Be honest; at times you too may struggle to take a knee and then stand up. That motion is essential to the barbell lunge. As with all these exercises, the lunge movement transfers into the real world. It makes you stronger and better able to stand up when you fall down.
Believe it or not, the barbell helps you balance as you lunge down and forward. As you progress in your training, you can even add weight to the bar. Advanced techniques also employ a jump into the lunge; this exercises your power output and tests athleticism.