It's using the size of the ruler, matching the posture as shown in the image. A few keys over and there's a picture of a grizzly bear that says it is 1m or 3'4" tall. And maybe when it's on all fours, that's a typical measurement to the shoulders - its arm length, more or less.

That's much shorter than the human at 1.7m or 5'7". From just those numbers, you might think that a human would weigh more than a grizzly or take one in a fight: But when a bear stands on its hind legs, it's 2.4m/8' tall and can be 800 lbs, I'd have put a grizzly way further to the right.