Each Star you control will have 3 numbers above it. These numbers correspond to the Economy, Industry and Science infrastructure that has been built at the star.
The number below a Star's name, or below a carrier shows how many ships are at the star or in the carrier.
If a star is within you scanning range, it will have a bright white icon and you will be able to see how many resources are available at the star. The size of the white ring around the star indicates how many resources are at the star.
When you select a star it will be highlighted in the map with a bright dotted ring. Your current Scanning Technology range will be shown as a faint dashed ring, and your current Hyperspace Technology will be shown as a faint spiky ring.
A carrier that has been ordered to make a hyperspace jump will have a line drawn from the ship to it's destination. If the line has a white highlight it means the carrier is in hyperspace and that it must complete the jump
Stars with warp gate accelerators will be rendered with a glowing ring, much brighter than regular stars.
You can quickly toggle the mini map using the Z key, or use the mouse wheel to zoom in and out. Player with touch devices may pinch zoom in and out.