Any macronutrient in excess can affect your weight loss goals. This could be too much fat, too much protein and yes it could also be too many carbohydrates. The thing to remember is usually not just the macronutrient or carbohydrates that are interfering with your goals but rather the type and quantity of those foods you are consuming.
Net carbs are used to track the number of carbohydrates that are actually being used by your body. This calculation subtracts fiber from total carbohydrates to leave you with your “net carb” value. Fiber is subtracted because your body doesn't absorb these. Many low carb diets track net carbs vs. total carbs because it allows you to include high fiber and more nutritious carbs without going over your daily carb limit.