Vane device comprises inner shroud, outer shroud, aerofoils. I cannot understand what shrouds are, and their function.
Generally speaking the shroud in a turbine engine is a flat plate located at the end of the blades which helps to keep the gases from "leaking" past the tips of the blades for better flow, and also to minimize vibration. A more detailed description can be found on the WENZEL America website.
In this photo of an interior blade of an RB199 turbofan engine the shroud is on the right.
RB199 blade (author: Stahlkocher, via Wikimedia Commons, CC-BY-SA-3.0)
Even though in most cases there is an individual shroud for each blade which butt up against each other, the entire structure is often referred to in the singular as a shroud. This diagram shows how it looks when the individual blade-tip shrouds fit together.
Turbine shroud (author: unknown, this diagram appears unattributed on multiple websites)
Turbofan engines essentially use the wall of the engine inlet as a shroud for the fan blades, as seen in this photo:
GE90 (author: Dysanovic, via Wikimedia Commons, CC-BY-2.0)
Although there was a question here about why the fan blades of turbofan engines don't have individual shrouds, and one of the answers included a photo of one that does, the F108 (CFM-56) engines that are used on the reengined KC-135 tankers.
F108 turbofan engine (Tinker Air Force Base)
I have seen the blade tip type of shroud referred to as an "outer shroud". I couldn't find anything explaining what an inner shroud is.