option-click

I should explain that I just bought my first Mac and I am using a standard keyboard for pc with it.

You hold "Option" on your keyboard, and "click" with your mouse. Currently you can use this to select bits of code and gain help on how to use it.

macOS offers two ways, usually to invoke 'options' in menus, as an example.

One involves holding the 'option' key, or alt, on a pc-centric keyboard while clicking, the other is by using a right-click on a two-button mouse, noting that a current wireless Mac mouse has one upper surface, but still acts like at least a two-button mouse. On macOS, this is referred to as a 'contextual menu'.

Users are encouraged to experiment with option-clicking to expose alternate menus in the applications they use.

See this microsoft document for pc keyboard mappings when used on a mac:

h t t p s : / / support.microsoft.com/en-us/kb/970299