This list contains currency rates, which allow you to recalculate amounts between different currencies.
All rates are saved in the base currency which is specified in Settings. If you use USD as the base currency, then amount in USD will be calculated by multiplying the amount in EUR by the currency rate.
If you change the base currency the values in the currency rates list becomes incorrect. In this case, it is recommended you erase this list and re-fill the currency rates.