How can I create a photo editing app on android studio?

If you want to develop a good quality photo editing app. First of all, we could recommend you to look at the most popular applications in this segment (like Aviary or Instagram) and pay attention, what they offer to users.
After that, you need to decide which features are essential for your application, and which of them can be skipped. The list of main features could be:
1. uploading photos (upload from the gallery of the device or take a photo with your camera directly app);
2. editing photos (make a unique set of tools),
3. saving photos
4. registration,
5. shop
Money and time estimation
We can conclude it takes about 836 – 1370 hour to develop an app (like Aviary). And if we multiply this result by $50 (average cost for an hour of developing) we get that this kind of app startup costs $41,800 – $68,500.

It's difficult to develop a photo-editing app if you are new to Android development. You should start with simpler apps and then go for such an app. I'd recommend you starting with a simple wallpaper app. Once you got it working, try to add basic photo editing within that app. Basic photo editing is easy on android. just google it

If you are new in Android studio then, first of all, learn basic things and features of an android studio and then start to develop simple and first level photo editor or wallpaper editor app. Watch the online video about how to make a photo editor app in Android.

I think that if you do not have the knowledge and experience, then you should think about hiring some kind of specialist, if this option is not suitable, then you need to study the technology on which you would like to create such an application and learn everything about video editing applications, for example in the Cleveroad article is written well, most likely you do not know which applications are liked by the majority of people, so you can create a thread on Reddit, I think everyone will be happy to answer you)

My brother is software engineer and he says it's a little bit difficult for the beginner but I think you have to try.

You need software developer.