The two companies are vague about exactly what services will be rolled out in the test. This is understandable since the 5G standard is not set yet, and this test is for sure part of defining that standard. But whatever the test includes it will take a lot of engineering efforts to make it happen. Being a digital designer based in the hometown of Ericsson of course I find this highly interesting!
Ericsson has a nice media kit available here with lots of information about 5G.
Earlier both Huawei and Ericsson have announced that they will test 5G technology during the 2018 football world cup in Russia. This is a tougher deadline time-wise; the football world cup will not be postponed. But covering two entire cities with 5G will require a more mature technology.