commercial code Vs Commercial software

hi

in page What Does Free Mean? <https://www.debian.org/intro/free.en.html>
in paragraph 6 part 3

write

Distribution of source code. One of the problems with most commercial code
is that you can't fix bugs or customize it since the source code is not
available. Also, the company may decide to stop supporting the hardware you
use. Many free licenses force the distribution of the source code. This
protects the user by allowing them to customize the software for their
needs.


i can not find any source about commercial code i know freesoftware
can be Commercial
software but what is the commercial code?


 i check wikipedia  <javascript:void(0)> but still have problem

i think if we write  proprietary software it is beter

thanks