Calling the function length() in R returns the number of elements in the matrix, or vector, so assuming you were looking at pieces in a puzzle, it would tell you how many pieces there were. It would give you the number of values, not what the values are. Length is the number of parts that make up the whole.
Saying to someone, 'what is the length of your dresser?' could lead to confusion. Both dimensions are about the same, so do you mean the height or the width? The value or the number of values? Length functions as a way to condense this two-dimensional spread of the object, a way to make things simpler. In asking 'what is the length of your arm?' we make the arm into a line, we forget the space across the skin has a size too.
Someone says, 'how long has it been since we last talked?' you may begin counting days, or (more likely) you may begin thinking about the values themselves, what has happened since then? Luckily, the answer to length is always a pleasant little number. A handy way to skirt the real question, the second axis, the value stretching out in the ten thousand times you opened your eyes.
Still, I wouldn't want to live in lengths. 'We spoke a few months ago', 'You live 1336 miles away', 'This writeup is 284 words long'. Length is even less than the number of parts that make up the whole. Length forgets that its opposite is the important part: the growth of my fingernails, the inches that make up your new baby. Length only goes on, like the sun rising. Length doesn't mean we're moving farther apart.