Number 5 is the jump fuel indicator
Jump gates or jump points are portals to and from different systems. To use a jump gate fly up to it. Often you will be checked for contraband as you approach. In order to use the gate you first must check to see if you have jump fuel by looking at the bar on the far right of the screen. If you don’t have any jump fuel go land on a planet to refuel (automatic) and than go back. After you have been checked for contraband and were deemed clear you can approach the gate, fly over the blue circle in the center and while over it press [J] to initiate the jump. An animation will start, then the screen will flash and you will appear at the other end. After exiting the jump gate you might again be subjected to a contraband scan.