I am developing an inventory management application i want to use AWS EC2 . which will have 10-15 users and storage about 2GB .as a newbie i could not understand the pricing can somebody help me how much it will cost me per month
With cloud solutions like AWS, this is not so straightforward to figure out like with "classic", always-on servers that wholly belong to you, and where you are paying fixed monthly prices for power, network, backup and rack-space, with maybe a little bonus on-top if you exceed some bandwidth limits.
So, in your case, have a good look at what "sizes" of VMs AWS has to offer. According to Wikipedia, in 2016, prices on AWS ranged from $0.0065/hour to $6.82/hour, depending on performance and other factors, with similar ranges for storage, and then further complicated by other factors of your plan (i.e., 3-years prepaid or whatever).
Secondly, you have to factor in when and how long you actually need your application to be available. If none of your users are working before 7am or after 9pm, then you can have the application running only in this time, not paying anything in the "off" time.
Thirdly, there are even more options. For example, maybe you can use lambdas for some functionality of your application (even more finegrained control over costs) and so on.
Lastly, there are things like spot prices, where you bid for unused resources at drastically lower prices. You might become creative here and run your background batch processes on such instances, for example.
More variations are mentioned in the comments.
So, you see, we cannot really predict what your application will cost. It would certainly be possible to give you a ballpark figure in the case that you would run your application 24/7 just like a classic VM, but that would be rather useless.
You need to sit down, read some more about the AWS pricing structure (they do have an online calculator where you can plop a few values in). As you are not doing a play or for-fun project, it would also be more than worthwhile to actually experiment, get an AWS account, develop a small prototype and do some performance tests so you see what you actually do need.
Check out their calculator at https://aws.amazon.com/tco-calculator/ if you didn't already, but be prepared that their breakdown of on-premise costs is, in my opinion, not very useful (you'd better figure that out yourself, if on-premise is at all an option for you).