Why canvas is so big?

I am watching the tutorial video"Survival Shooter tutorial/Health HUD",but i can't understand the explanation in the video. 03:17 - 03:21 and I just wanted to clarify it's so big because 03:21 - 03:24 it maps 1 pixel per unit, world unit 03:24 - 03:28 so that we get the highest level of fidelity in our graphics. 03:28 - 03:30 So if you have a graphic that is 03:30 - 03:33 512 pixels by 512 pixels 03:33 - 03:38 it's going to be drawn 512 units by 512 units. 03:38 - 03:40 And if you recall the capsule collider on our character 03:40 - 03:42 is 0.6 units wide 03:42 - 03:46 so 512 units is very very big. 03:46 - 03:48 So that's why you're seeing the canvas display 03:48 - 03:50 huge in here and then the level looking tiny 03:50 - 03:53 down in the corner, it's nothing to worry about whatsoever.