As the others have intimated, it's 1cpp when redeeming on travel-related purchases, and 1/2 cpp when redeeming on other purchases.
Also, perhaps a helpful hint. If you convert your card to another Barclay product that redeems 1:1 (e.g. the Barclay Rewards card), your points will transfer to the new account, where you can then redeem them for 1cpp instead of 1/2 cpp. This can be particularly useful, for example, if you've had the Arrival+ for a year, you've amassed a bunch of points getting 2% cashback wherever, you want to cancel the card before the annual fee kicks in and you don't have enough travel-related expenses to redeem out all of your rewards. No sweat. Rather than cash out what's left at 1/2 cpp, just call and convert your Arrival+ to a fee-free card like the Barclay Rewards, then once you get that card you can cash out your points at 1:1 without needing travel-related expenses. Of course, you won't get the 10% bonus on travel redemptions, but it's better than losing half the value of the points, or (IMO) having to pay an annual fee.
Chris.
