The Press a Button action presses a named button in the front window.
Note: button names may be case sensitive. Remember too that sometimes buttons change names, for example Show sidebar may become Hide sidebar after being pressed.
The action allows you to specify multiple options separated by a vertical bar (eg This|That) to allow for toggling or varying buttons. They will also ignore the difference between three dots (...) and an ellipsis (…) so you do not have to worry which one is used.
Alternatively, you can start the name with an ^ and use a regular expression to match the button name.
As of v7.1+, you can use Text Tokens in the field.
As of v10.2 there is an option (in the action (gear) ⚙ menu) to have this action wait until the button exists and is enabled and then press it.