It is the carrying weight of a item. Stamina depletes faster and regenerates more slowly the larger the sum of the weights of the carried items.

From what I could think of. There are three levels of safety with weight, and are the levels

0 - 30 | Safe

40 - 50 | Kinda Dangerous

50 - 75+ | Really Dangerous

100+ | Caseoh Heavy Dangerous

The numbers might not be accurate, but make sure you keep an eye out of your weight. If your slower than a snail, then you wont outrun any entities.

Here is a list of items with there weight

0 - 16

Perfume bottle: 0
Pill bottle: 0
Plastic fish: 0
Toothpaste: 0
Toy cube: 0
Extension Ladder: 0
Flashlight: 0
Spray Paint: 0
TZP-Inhalant: 0
Walkie-Talkie: 0
Remote: 0
Teeth: 0
Rubber Ducky: 0
Dust pan: 0
Airhorn: 0
Laser pointer: 0
Bee Hive: 0
Whoopie-Cushion: 0
Clown horn: 0
Garbage Lid: 0
Kitchen Knife: 0
Plastic Cup: 0
Shotgun shells: 0
Zed Dog: 0
Stun Grenade: 0
Weed Killer: 0
Easter egg: 3
Coffee mug: 5
Pro-Flashlight: 5
DIY-Flashbang: 5
Old phone: 5
Toilet paper: 5
Stun Grenade: 5
Hairdryer: 7
Red soda: 7
Candy: 11
Zap Gun: 11
Egg beater: 11
Hair brush: 11
Magnifying glass: 11
Comedy Mask: 11
Tragedy Mask: 11
Player Body: 11
Shovel: 14
Cookie mold pan: 16
Golden cup: 16
Jar of pickles: 16
Boombox: 16
Large axle: 16
Lockpicker: 16
Magic 7 ball: 16
Ring: 16
Steering wheel: 16
V-type engine: 16
Double-barrel Shotgun: 16
Control pad: 16
Belt Bag: 16

19 - 26

Big bolt: 19
Bottles: 19
Radar-Booster: 19
Flask: 19
Gift Box: 19
Soccer ball: 19
Tea kettle: 21
Fancy lamp: 21
Stop sign: 21
Robot toy: 21
Toy Train: 21
Brass bell: 24
Tattered metal sheet: 26
Clock: 26

31 - 84

Apparatus: 31
Painting: 32
Chemical jug: 32
Yield sign: 42
Jetpack: 52
Gold bar: 77
Cash register: 84

Thank you for reading this guide. I hope it help...