The System Info gives an overview of the star system. To the very left is a schematic depiction of the system with the star in the middle and the planetary bodies with their orbits. Systems can contain planets, moons and asteroid belts.
At the top of the view is the stellar class of the system. Detailed info on the star, as seen on figure 1 also shows Solar Activity and the number of planets. The planet icon in the top left of the System Infos switches to a 3D view of the system as it would look in battle. Stations are also visible in the 3D view.
In case the system is owned by the player there appears a button below the stellar class of the system to designate the system as "open" or "closed". If the button reads "Open System", the system is considered "open" and the player empire's private sector can try to colonize planets or build mining stations in the system. Basing freighters in an open system is also an option for the private sector.
At the bottom of the System info are 4 buttons which allow access to the following menus (from left to right):
- Build Menu
- Repair Dialog
- Fleet Manager
- Battle Rider Manager
Stellar types generate semi-realistic expectations of surrounding planetary bodies based on the common theories of a few years ago.  In game, this produces different randomization parameters for star systems. Star type influences number of possible orbits. Star size dictates how many of those orbits get swallowed by the sun. Orbital position from star dictated planet type. 
The rule of thumb is:
Red Dwarf stars usually have low numbers of planets with possibility of no planets at all.
Orange and Yellow Dwarfs / Main Sequence stars like our own sun have a good chance of multiple planets and usually a gas giant or two (possibly with moons).
Giants usually have large numbers of planets but the inner orbits are taken up by main stars so there is a higher chance of gas giants and moons.
Super giants have few to no planets, again due to the size of the stars consuming orbital positions over time. 
You will find stars of size Ia, Ib, II, III, IV, V, VI, and VII, where VII is the smallest and Ia is the biggest. Star Type corresponds to the Star color (so Type O will always be blue, while Type G will always be yellow).
Solar activity is always 5 and seems to have no impact.