It doesn't show folders but clicking the text "14.8 of 15 GB used" or this link[0] will take you to a list of the biggest files, at least in drive. You can also go here[1] to see what services are using the most data.
Thanks. I came back to add the same info, found by googling, that the storage amount includes other Google services. (my space is mostly taken up by photos + gmail, because I've cleaned out google drive in an attempt to get the usage down, not realising that it wasn't the issue. Looks like I'll be spending hours painstakingly deleting photos and emails...