identation is the mechanism by which a code block is represnted in python. Unlike languages like Java or C++ where the code block is represented by curly braces, in python the need of putting and montitoring the start and end of barces was elemenated

Since there is no other way of representing code block, hence the need of indentation becomes unavoidable

For Example:

Java

int add(iint a, int b)
{
 return a+b;
}

Python

def sum(a,b):
 return a+b

Yes, Where in other programming languages the indentation in code is for readability only, in Python the indentation is very important.
Python uses indentation to indicate a block of code.
Example:

if 5>2:
 print("five is greater than two")