“Across” is a preposition that refers to the action of moving or reaching from one place to another. Because it is a preposition, it is followed by the object of the preposition — that is, place/thing that is being crossed. Example: “He stretched his arm across the table.” “Far” means that the movement was a long one. So, here, “far across” means “Moving a long distance,” and it is followed by thing that was moved across (namely, “the distance and spaces between us.”

do you know what across means, such as "the school is across the street"? Far means a long distance away. Sometimes you see the expression "far away", such as "portugal is far away from Brazil" Example of far across The boat left Portugal and sailed far across the Atlantic Ocean until it reached Brazil