Everything you buy online goes through this extra layer of security provided by Visa Secure.
Based on your previous purchase history and information such as what devices you've used to shop with online in the past means that most of the time this extra security layer will work automatically and you won't need to do anything.
If you're not asked to confirm it's you you'll see a message saying Barclaycard is currently verifying your transaction, so you'll know your transaction is being processed.