What is the explanation of 9:5?

I am having trouble understanding this following verse. **Quran 9:5** > But when the forbidden months are past, then fight and slay the Pagans wherever ye find them, and seize them, beleaguer them, and lie in wait for them in every stratagem (of war); but if they repent, and establish regular prayers and practise regular charity, then open the way for them: for Allah is Oft-forgiving, Most Merciful. Is it really saying that holy war is encouraged by Quran? My friend tells me it is just a bad translation. Can anyone deeper explain what it means, if you speak Arabic. Disclaimer: I am not from a religious family nor have I been taught about Islam properly, I just recently picked up Quran to explore it on my own.