I believe there is a small bug in the feedback messages given by the QLDB PartiQL Query Editor.
See below for an example.
The values for latency, I/O and transaction ID seem to be mixed up.
23:53:56 queries took 0.388 seconds at 1 (Total server-side latency: CsRoFJrgU9xKsKUQuHFwrm sec, total read I/Os: 0.008, transaction ID: 3)