Linux Containers (LXC) are OS-level virtualization methods for running multiple isolated Linux systems on a single host. This means that you can run Linux distributions (such as Ubuntu, CentOS, Debian, Fedora, Alpine Linux etc) as long as the kernel version is the same or newer than the host.
You can’t run non-Linux operating systems like Windows, macOS or BSD natively because LXC relies on the Linux Kernel features. However, technically, you can run Windows using QEMU or KVM inside the LXC, but it is not the conventional and efficient use-case for LXC.