The variable token.visible controls the visibility of the token to players during a game. The variable can take two values, 0 (not visible) or 1 (visible to players). This is equivalent to the "Visible to players" option on the right-click menu for tokens.
Getting Token Visibility
Will return 1 if the token is currently "Visible to players," and 0 if it is not.
Setting Token Visibility
[token.visible = 0]
Will set token.visible to 0 - e.g., making the token invisible to players. A more useful approach might be:
[token.visible = 1 - token.visible]
This creates a "toggle" macro that will alternate token.visible between its two possible values each time the button is clicked.