A reading unit of capacity that the implementation of a strong consistency read on the size of the project up to 4 KB per second, or perform twice per second reads with eventual consistency.
A write unit of capacity that the implementation of the project the size of the write once up to 1 KB per second.
https://docs.aws.amazon.com/zh_cn/amazondynamodb/latest/developerguide/ProvisionedThroughput.html