re: Can someone explain 'currency war'?

It's a media creation to dramatize something that's been going on for decades with little notice.

It refers to countries trying to stimulate their manufacturing industry and economy by lowering the value of their currency. That makes goods manufactured in their country cheaper in other countries and therefore, more likely for people in other countries to buy their products.

It also makes products made in other countries more expensive within those countries with a devalued currency so citizens tend to buy less foreign made goods and more domestically manufactured goods which again stimulates the manufacturing industry in that country.

Japan is actively pursuing that process now and has been for several months. China is notorious for keeping its currency cheap versus the US dollar.