Steps to generate Signed APK:
Open your project android folder with android studio.
Wait for a while to build gradle with files(5 to 6 minutes) .
After successfully gradle sync.
In the menu bar, click Build > Generate Signed Bundle/APK.
Select APK from the drop down. Press Next
Select a Key store path or you can create a new one after fill some basic information.
Enter Key store password
select default key alias.
Enter key password
Select Destination folder with APK modes(debug , profile or release).
Choose signature version V1 (jar signature)
After that Press finish. It will take 5 to 6 minutes(approx.). And then you can locate you APK at destination folder.