Translation:This vase is very expensive.
ビールが高い(biiru ga takai) would be expensive, as you wouldn't normally call beer tall, and 背が高い(se ga takai) would be tall, since a person's height isn't generally expensive. In regards to the original sentence, vases can be both tall and expensive, but I feel in a shopping context, someone would be more likely to comment on price than size.
I see a few comments stating that you should know if 高 would mean tall or expensive by context. However no-one really answers the question: How should I know which one to use in this particular sentence? A vase could be called tall as well as expensive. Shouldn't DuoLingo accept tall as a valid answer then?
I put "This flower vase is very tall" and got marked wrong. There's no reason a vase can't be tall, how was I supposed to know they were using takai to mean expensive here :/ I think tall should also be an accepted answer tbh. I see there are multiple comments here saying the same thing, some from up to a year ago. Duo should have fixed this by now.