Generally speaking weight loss and maintenance is when you are in a theoretical calorie burning deficit. This means you burn more calories (e.g through exercise and daily movement) than calories you consume (which can be lowered by dieting for example). This deficit is then was helps to *contribute* to weight loss, but it isn’t the only factor.
At the end of the day your weight isn’t necessarily something to worry about, in that two people who both weigh the same can be at very different health levels.
E.g two people could both weigh 100kg. Person one has 5kg muscle 5kg fat, and person two has 1kg muscle 9 kg fat. So these two people who weigh the ‘same’ aren’t in fact equal. This is why worrying about weight alone and this whole ‘weight loss’ thing isn’t necessarily important or relevant anymore, it’s more about your actual health and nutrition.
Calories are also largely an irrelevant measure. A calorie in itself is the same no matter if it came from a bar of chocolate or a piece of lettuce. It’s the nutrition, vitamins, sugar, fat, energy levels in a food that are important, not the calories.