Is it true that the operating system’s correct name is GNU/Linux?

That depends upon whom you ask. Those with the GNU Project, having worked long and hard to create the tools that make an operating system useful (utilities, compilers, and applications), want their diligence recognized. Because nearly all “Linux” systems consistlargely of GNU tools and the Linux kernel, this isn’t unreasonable. On the other hand, many people feel that GNU/Linux is too awkward to use as the primary name for an operating
system. In any event, the choice is up to you: Linux or GNU/Linux, it’s all good.