This concerns the proliferation of the predator talent in the campaign.
The idea is this:
Predator has an additional/alternate requirement, you can only use it against ships that you have an Ace rating against, meaning 5 kills. So if you have taken out 5 TIEs, you gain the predator against those ships. Take out 5 defenders, and predator against those, and so on.
It makes keeping track of kills worthwhile, beyond the always fun bragging rights, and rather than everyone buying it, as my friend suggests they do, it is free, but you have to get the killing blow against that ship type to earn the ace status.