This means the plugin is compiled for . If you are using a modern computer (Windows 10/11 or macOS Catalina and newer), you use x64. If you tried to load this on an old 32-bit DAW, it would simply refuse to scan.
C:\Program Files\Common Files\VST3\WaveShell1-VST3 13.0-x64.vst3 vst plugin waveshell1-vst3 13.0-x64 -vst3-