The phrase "added caffeine" means that caffeine, which is a natural substance that gives you energy, has been put into something that didn't originally have it. Full definition
For people seeking an energy boost, companies are increasing their offerings of foods with added caffeine. (sandiegouniontribune.com)
In addition to limiting their caffeine content, foods containing added caffeine must also have a statement on the label that the product contains caffeine. (australianbeverages.org)
The matcha in this vegan version does add some caffeine (along with antioxidants) to the mix, so it's a great way to get your morning started! (franceslargemanroth.com)