How to Generate signed apk with android studio

Go to Build->Generate Signed APK->Next (module should be your current module)
Click on create new
Fill the form with the required details. Click on icon that will open up a navigator window which will ask you to select a .jks file. Navigate to a folder where you want your keystore file saved and then at the File Name box at the bottom of that window, simply enter a name and the press OK button. .
Click on Next and then select Release, now you are done.