it looks like a typical element in a fan oven. The backplate is part of the element (not removable from it) and possibly has studs or bolts protruding through the oven wall and retained by screwing on the reverse side. on reassembly, use copper grease on the studs as it continues to lubricate even after heat. looking at your pic I think I can see two hexagonal heads of bolts that can be undone with a small socket spanner and T-bar. there may be nuts on the other side.
or the backplate may hold the plug-in support, and can be pulled out, you will find a socket behind it.
if you look at the new element its attachment should be clear.