A jump shift response normally means “I have 16+ points with a good suit” and is forcing to game.
However consider the following situations
1. You are a Passed hand with 9 -11 points and 4+ card support for Partner plus a good suit of your own such as, after a 1 Heart opening ♠ xx ♥ Kxxx ♦ KQJxx ♣ xx.
2 Partner Overcalls
3 The opposition overcall between you and your partner
With 9 points but 8 losers you would normally consider bidding 3 Hearts but 3 Diamonds gives partner two pieces of information at the same time so they can work out how well the two hands fit together
Unassuming Cue Bids and pre-emptive raises take care of most hands with support but remembering that a second seat overcall should have certain strength a Jump Shift can show the same sort of hand as in (1) inviting Partner to consider bidding on with this more accurate information. If you were any better you may just punt for the Game.
Partner opens 1 Heart , next hand bids 2 Clubs, 2 Diamonds from you would be forcing if you weren’t a passed hand so a jump to 3 Diamonds would be yet another Fit Showing Jump. If by chance you had a 16+ hand (unlikely but possible) with or without support there are plenty of other ways to deal with it. There will be sequences where you can’t use this method. If the bidding was as above and you were a Passed hand and the opposition bid 2 Diamonds and your suit was either Spades or Clubs you probably be best just supporting partner with a 3 Heart bid and not risking Partner passing your bid if they had opened light