In the menu bar, click Build > Generate Signed APK.
Select the module you would like to release from the drop down and click Next.
To Create a new keystore, click Create new. Now fill the required information and press ok in New Key Store.
On the Generate Signed APK Wizard fields are already populated for you if you just created new key store otherwise fill it and click next.
On the next window, select a destination for the signed APK, select the build type and click finish.