shmee was what you'd usually call a "house slave" and she would cook, clean, get groceries, handle errand, and perform minor stewardship tasks like delivering important documents or handling day to day affairs in a shop as a clerk
anakin was really too young to any any "actual" slave work like hard labor or protecting watto but he was clearly intelligent and good with machines so watto had him scouting around tattooine and collecting droid scrap to build new droids, likely to sell
as mentions watto clearly had an eye for strong investments and probably expected anakin to grow up into something of a circuit racing gearhead genius who could rake in credits with pod race tournies, droid repairs, and outright sales flipping previously destroyed droids
historically speaking male slaves were much more valuable for obvious reasons. at a certain point a female slave just becomes a mouth to feed and since watto had no female counterpart to speak of there's little use for her as a matronly aid so she probably would have been sold off at some point around young adulthood for anakin unless he could convince watto to keep her and double-down on the grind in exchange for her continued safety as watto's chattel
on a planet as dangerous as tattooine it's very likely better to be a slave to a decent master than a penniless wretch on the street dying from sun(s) exposure and dehydration