Jump Gates are used to travel through hyperspace between systems.
Most jump gates allow travel in both directions, but some only allow travel in one direction. A list of jumpgates and their destinations can be found on individual system pages.
To use a jumpgate, fly a ship within its signal range and click the prompt displayed in chat. Your ship must have a navigation computer and a hyperdrive that is fueled with at least two pieces of chetherite per hopper.