The term Win32 is used in various contexts.
By Win32 a family of 32-bit Windows operating systems for the architecture x86 is understood.
By Win32 a 32-bit API is also understood which is provided by the 32-bit Windows operating system.
There is a subsystem WoW64 on new 64-bit Windows systems to provide compatibility with obsolete 32-bit applications. The system translates the calls of the 32-bit API into the calls of the 64-bit API, redirects requests when working with the register and files and performs some other functions.