Software OpenGL is a SolidWorks setting that will tell SolidWorks to emulate OpenGL on it's own and not attempt to use the OpenGL support of the graphics card driver. In the "old days" this was used a lot on systems whose graphics drivers had no OpenGL support at all; Software OpenGL will automatically turn on when no OpenGL support is detected.
Most graphics cards these days will at least emulate OpenGL and therefore support the use of OpenGL calls from application software like SolidWorks, so that’s why SolidWorks did not automatically turn on the Software OpenGL option even if you're using an unsupported "consumer/game" graphics card.
Software OpenGL as a user-selectable option is useful for troubleshooting graphics card and driver problems, and in addition SolidWorks often performs better when you tell it to ignore the emulated OpenGL support on game and consumer-type graphics cards.
To set the Software OpenGL option in SolidWorks, you must open SolidWorks but have no parts, assemblies or drawings open. Then you can go to Tools > Options > Performance and toggle the option as needed. If you have a file open in SolidWorks when you try this, the option will be greyed out. Just close all data files but keep the SolidWorks program running and you will have access to the checkbox.