1.
rate, exchange rate
A ratio or price at which one thing is exchanged for another, especially currency exchange rates. Also used more broadly for rates in finance and pricing.
Usage
Most commonly used in the context of currency exchange (為替レート). In online games it also means a player's rating: レート戦 (rated matches).
The Sino-Japanese suffix 率 is used in compounds like 利率 (interest rate) and 税率 (tax rate), while レート is preferred for exchange rates and informal rate discussions.