The Scouting sub-screen provides you with a detailed scouting report on the currently selected player, including a text description and a history of the player's previous scouting reports, which can give you an idea of his developmental progress:

The player scouting screen is composed of several different panels, the exact contents of which can be configured as desired via the dropdown menus above each panel, in a manner similar to the Manager's Office screen.

The scouting reports themselves are described in detail in the Scouting Reports section of the manual.