Very confused about calories burned

I don't quite understand the concept of BMR or sedentary calories burned; does that mean the same thing. If in fact it does meant the same thing, how does that compute with the calories burned doing exercising?

I weigh...184 and am 5'5" I would like to get down to 145.I used the burn meter  and it states that I burn 1900 calories during a typical day. I also did the calorie target calulator and it states that I should eat 1350 calories a day to reach your goal weight.

So am I burning more just by doing nothing than I am eating? That doesn't seem right. Also since I am naturally burning 1900 calories and I burn approx. 400 calories by exercising is that a total of 2300 calories I am burning?

I am sooo confused. I hope my message makes sense. Thanks for any advice.

I think it means the calories you burn just being alive and living

You would add your exercise on top of the BMR. So if you burn 1900 and exerecised off 400 you've burned 2300 that day.

Thanks for both of your replies. For some reason, today it makes sense. I was racking my brain last night trying to figure it out!