Spot rate is the price of a currency today. A spot transaction involves delivery within a short standard period, typically one to two business days, rather than instantly: settlements require time.
It contrasts with the forward rate — the price of a currency for a transaction executed in the future. The difference between them is not a forecast of the exchange rate: it is determined primarily by the difference in interest rates for the two currencies over the corresponding period.
Therefore, the forward rate for sum pairs is usually higher than the spot rate — this reflects the gap between sum and foreign currency rates, not the market's confidence in sum weakening by a specific amount. It is useful to keep this logic in mind when comparing the returns of sum and foreign currency instruments.
In practice, the spot rate is what a participant sees during ordinary conversion, while the forward rate is applied when fixing a future transaction and in corporate hedging.