A sleigh is a large sled that can hold multiple people. Sleighs are used to transport people or things across snow and ice. Sleighs are usually pulled by horses.
You slice something up by cutting flatpieces off if with a knife. When you are taking many slices off something, you try and make them all the same thickness.
You slide along a slippery surface by moving across it without ever breaking contact with that surface. The people in the picture are sliding down a waterslide.
A sling is a way of carrying a baby around. A sling is made from a piece of fabric, and goes over your shoulder. Babies like slings because it keeps them close and snuggly.