QEMU is a fast processor emulator. Once upon a time there was only one package named `qemu', with all functionality included. These days, qemu become large and has been split into numerous packages. Different packages provides entirely different services, and it is very unlikely one will need all of them together. So current `qemu' package makes no sense anymore, and is becoming a dummy package.
If you want full system emulation of some architecture, install one or more of qemu-system-ARCH packages. If you want user-mode emulation, install qemu-user or qemu-user-static package. If you need utilities, use qemu-utils package.
This package can safely be removed.