"银杏萃取液" can be translated into English as "Ginkgo biloba extract" or more specifically as "Ginkgo biloba extract solution" if you want to emphasize that it's in a liquid form.
Ginkgo biloba refers to the species of the ginkgo tree.
Extract denotes the substance obtained by extracting components from the plant.
Solution (optional) clarifies that it's in a liquid state.
In most contexts, "Ginkgo biloba extract" would be sufficient and widely understood.