How to save the game?

Can someone please explain how does the Save & Load system work in the game?

I did not find any button for save. Is there a way to save the game session at any time?

U can see about _saveSystem.SaveDataToDisk

https://learn.unity.com/pathway/junior-programmer
In this Pathway, you will find the solution to your problem related to saving and loading. I also learned it from here. I watched a lot of tutorials on YouTube and also read some StackOverflow links but these tutorials can’t be taught me the JSON way of saving and loading. To understand the save and load concept using JSON, you should see the “Manage Scene Flow and Data” section of this tutorial. Unity Technologies explained these concepts in a very great practical way. Although, there is also a simple way of saving and loading which is using PlayerPrefs.