Glossary
Save
In one line: Stopping play in a lost round to keep your gun and armor for the next one.
What it means
Saving means hiding or staying away from the action when a round is already lost, so you do not die and keep your gun. A saved rifle is worth almost 3000 credits next round.
You save when the odds of winning are tiny (say 1v4 with little time) and the team's economy needs it. You do not save out of fear when the round can still be won: three players saving in a 3v3 throw away an even round.
An example
The spike is about to blow, you are 1v3 and far from site. Instead of running to an almost certain death, you hide in a far corner. The round is lost, but your Vandal and armor carry into the next one.