MIMO, active beam steering and paths with reflections. In theory. In practice, we'll see, but probably you'll have to hold your phone high to provide some clear line of sight between the antennas if you want those blazing fast speeds.
I'd recommend watching this video of a real-world 5g test https://youtu.be/_CTUs_2hq6Y - The speeds are >1gbps when you're effectively next to the 5g nodes, while it would reach <400mbps while going around walls and would jump between LTE and 5g (in an attempt to be on the fastest network).
