Help me in solving PYTH40 problem

My issue

i did not understand this topic

My code

# Update your code below this line

Learning course: Learn Python
Problem Link: CodeChef: Practical coding for everyone

The first line stores a string “NumeroTres” in the variable txt. The next line is a function that reads the length of the string stored in the variable txt and this function stores its result in another variable len_txt. Finally, we are printing the length of the string stored in len_txt. Elaborate your doubt to get a detailed explanation.