This lesson explains how to input two numbers, add them, and print the sum in Python. Initially, inputs are treated as strings, causing concatenation instead of addition. The `int()` function converts inputs to integers for correct addition. A type error occurs when printing the sum with a string, fixed by using `str()` to convert the sum. The lesson also covers converting to `float` for decimals and `bool` for logical values, where non-zero numbers and non-empty strings become `True`.