Walking as a form of exercise is one of the best. It's easy on your body, you do not need to buy any new equipment or clothes and you can do it anywhere. Walk to your TV, walk to your refrigerator or walk to couch. But seriously, how about waking around your neighborhood, walking to work, or walking up the stairs instead of taking the elevator. Now that's good exercise.
But will walking help you lose weight? Maybe. Walking will help you lose weight if you currently do nothing. What I mean is if you are a couch potato and walking would increase your daily activity. If you currently have a fitness buff and you stop running and walk instead, obviously it would be a decrease in your daily activity. But let's assume you are starting from ground zero with little or no daily physical activity. If you start walking on a regular basis you will expend more daily calories. You will also increase your metabolism initially which will aide in weight loss. After you have lost some weight, your body will ever adjust to your new lifestyle of activity and calorie intake. This means it will slow down your metabolism to maintain this weight. Otherwise, you would have to eat an ever increasing amount of food based on your activity.
Now let me quickly mention what the scale says when you step on it. It could be telling you that you are now heavier. Please look in the mirror and affirm how you look and feel. If you are losing weight from walking but gaining muscle from your new activity of walking, you could actually gain some weight. Do not forget muscle is heavier than fat!