USD/ZMW is the anchor Kwacha rate. Copper, Zambia's main export, is sold in US Dollars, so the Kwacha's value against the Dollar reflects how much foreign currency flows into Zambia relative to how much is needed to pay for imports, fuel, and debt service.
Copper is the key common thread. Because it is priced in Dollars and Zambia depends on it for most export revenue, rising copper tends to strengthen the Kwacha, while falling copper tends to weaken it. Chinese demand (China buys most of the world's refined copper) is therefore an important background driver.
The US Dollar is a traditional safe haven. In periods of market stress, investors tend to move money into it, which often pushes it higher against the Zambian Kwacha even when local economic data is unchanged. Because the Zambian Kwacha tends to do well when investors are optimistic, USD/ZMW is widely watched as a barometer of global risk appetite.
The Zambian Kwacha is an emerging or frontier-market currency. Compared with a major reserve currency, its market is thinner, so shifts in global risk appetite, Dollar liquidity and capital flows can move it faster and further than fundamentals alone would suggest.
Central-bank policy matters on both sides: the Federal Reserve (Fed) and the Bank of Zambia (BoZ). When one of them is expected to keep interest rates higher than the other, that currency usually attracts capital and strengthens; a narrowing gap tends to reverse the move.