Statoscope is a tool to view and analyse data logged on a per-frame basis, and more generally it is the system that produces and manages that data.
In essence then, it provides a way of recording values (e.g. fps, number of drawcalls etc.) from CRYENGINE and a way of showing how the values change over the course of a play-through or over several play-throughs.
Chapters:
The viewer (shown below) aims to present the recorded data in useful ways, such as visually in a plot that supports filtering and zooming, basic processing (averaging, local max), stats (min/max/average, buckets), comparison with other logs or with target lines and display of in-game screenshots and user markers for gameplay reference.