And "I don't understand" should not be acceptable. Let them write out what they did and what exactly they don't understand.
For example:
To find out more about main, I searched for "Java main", and got the following: "All Java programs must have an entry point, which is always the main() method. Whenever the program is called, it automatically executes the main() method first. " Yet when I look at this code here, line ref/ code snippet, I don't understand why it doesn't have a main....
I don't have any natural talent for programming nor math, and cried for 2 weeks straight when I was going through my first programming book, my brain literally hurt. I just ground that book.
Taking a book and typing out all the exercises, muscle memory. You work your ass off for 10 years, and suddenly you get lucky.
But even when I send them some references they reply saying even they read it they could not understand what it meant.
Which lead me back to explaining them from the beginning