What is the experimental gameplay? Have seen it many times but what exactly does it do and what changes are there?
The experimental gameplay is nothing else than the latest version in the Bedrock version, 1.15.2 (Java). If you do not activate this you will play on 1.13.2 (I guess)
You use content that is classified as experimental. I tell you from experience that nothing happens. You can then use Structure Blocks, Structure Void Blocks and a few other things.