As shown in the figure the market for US dollars(USD) is discussed. The equilibrium exchange rate is 0.6 euros= 1 US dollar.
At 0.7 euros per dollar, there would be an excess supply for USD. At 0.5 Euros per dollar there would be excess demand for USD.
One of the causes of change in exchange rates is inflation
rates. Higher inflation in any country relative to other
countries leads to currency depreciation.
If USA experiences a higher rate of inflation than other countries, demand for its exports falls (decrease in export competitiveness) as other countries get goods/services from USA at higher prices; at the same time, imports from other countries with lower inflation rates increase as USA gets them cheaper.
The fall in USA exports causes demand for the USD, to decrease, while the increase in imports causes supply of USD to increase.
This graph in question shows that rate of inflation in USA is higher than Eurozone countries.

Daily Exchange Rates: European Euros per U.S. Dollar 0.98 0.96 0.94 0.92 0.90 0.88 0.86 0.84...