Muscle is more dense than fat!
5 pounds of muscle vs 5 pounds of fat!
Muscle is more dense than fat, so gaining muscle while losing fat makes you look leaner and more defined. Muscle tissue burns more calories than fat tissue, so building muscle can help you lose weight and keep it off. Strength training can help you build muscle, but it's not the only factor. Nutrition and recovery are also important.
As you can see in the picture above, 5 pounds of fat represents a lot of volume added on to your body. Not only that, but the fat is partially held below the skin (subcutaneous) and will make your physique seem smoother and less athletic. By dropping bodyfat and maintaining or gaining muscle mass, your body will be leaner and will appear to be much more shapely as the layer of fat decreases.
Many women are afraid to gain muscle and look "too bulky" however a gain in muscle with a reduction in bodyfat results in a feminine physique that looks lean, sleek, and athletic. The most important thing to focus on if you are carrying extra body fat is to look to safely and sustainably reduce it. Not only will this result in a more athletic physique, it will also help your overall health and likely will reduce long term risk of chronic disease.