In the top picture you can see one lady is buying oranges from a outside trolley. Imagine it’s an outer function where oranges are a variable. That lady brings those oranges to home . Now you think she is inside inner function. Now she wants to have a glass of orange juice . So she cuts few oranges and squash it and pour it in a jar. In this process she is returning a juice served in a glass closure within buying oranges.
A Closure is a combination of function and lexical environment where this function was declared. The environment may consist of both local variables declared in the body of a function and global ones declared outside of the function.