Wallaby is an umbrella term that they use to describe anything that is smaller than a kangaroo. So the six largest species that look like this are the kangaroos, and everything smaller than them is a wallaby. These are specifically Bennett's Wallabies, also called Red-necked Wallabies, not because they're hillbillies but because they have a red tint to their fur.
Wallabies are marsupials. Almost all marsupials are native to Australia and New Guinea. The only ones we have in the Americas is the opossum, so we kind of got the short end of the stick on that one. This species in particular is native to Australia. They are all over the place down there and they come into your yard, eat the grass, poop everywhere and cause quite a few car crashes. So there they are considered a nuisance, but here they're just adorable.
Being marsupials the girls have pouches to keep their young, while the boys do not. You also have to age wallabies as 'out of the pouch'. This is because the gestation period is only about a month, so the baby is born so small you'll likely miss the birth. Once you finally see something you can start aging it.
The front legs on the wallaby are adapted for grabbing, clawing, digging, and grooming so they have very sharp nails. Some people tend to trim them like dog nails so that when you're in there with them they don't accidentally claw you when they're playing. We don't do that here, instead we have a blue ball for playtime. The back legs are very powerful and they are for jumping. If a wallaby needs to move a long distance or quickly they will hop, if it's a shorter distance or they want to move slowly they can crawl on all fours. The tail in the back is for balance. They can also rock back on it to punch or kick with their back legs. Typically this is only done between two males, but the wallabies are not nearly as aggressive as the kangaroos. The tail is also the best place to grab them safely. You grab them at the base of the tail, lift up, and then you can wheelbarrow-walk them to wherever you need to go!
Pictured Above: Wally (male), June-Bug (female)