In situations of economic uncertainty like we are facing right now, the best defense for your hard earned dollars is to be as well-informed and educated as you possibly can. Following the news that impact the markets, researching companies and following the markets should be a full-time job (unless you want to risk your money... you are probably better of at a roulette table).
The currency exchange rate is the rate at which one currency can be exchanged for another. It is always quoted in pairs like the EUR/USD (the Euro and the US Dollar). Exchange rates fluctuate based on economic factors like inflation, industrial production and geopolitical events. These factors will influence whether you buy or sell a currency pair.