The directories in
/proc/sys/net/ipv4/conf are neither hardlinks¹ nor softlinks¹. But that is of no interest.
The important thing is, that procfs (proc filesystem) is a special filesystem, usually mounted at /proc, that presents information about processes and other system information in a hierarchical file-like structure, providing a more convenient and standardized method for dynamically accessing process data held in the kernel.
In other words the procfs provides a method of communication between kernel space and user space. The files in the procfs show the content of variables in kernel space. And the kernel is the piece of software, that communicates with the hardware of the computer.
¹) As mdpc said,
ls -l shows the link count in the first line. And that is zero in the procfs.