is no-code, something like using predefined codes?

Using GUI tools which usually require Code to set up.

Also model based development; the idea that the analysis and design of a system is what it takes to implement it, so automating implementation from diagrams is more precise and less error prone than having humans type the code — it's not faster or cheaper as the analysis and design needs to be much more elaborate and complete, but it makes the system more reliable and predictable.

https://n8n.io
is a good example of "no code"

It's like modern day scratch
https://scratch.mit.edu/

Essentially "no code" is a drag / drop gui where you add blocks on to a screen and not write 90% of the underlying code and stick with the core logic and be done in half an hour.