What does assertion mean?

Answer 1

Assertion means checking if the given condition is true. If the condition was false then you will get an error generally.

You will find assertion in python too.
Check this: https://www.sololearn.com/learn/Python/2444/

Answer 2

Assertions in python.
Check this link.

https://www.programiz.com/python-programming/assert-statement

Answer 3

What language? Javascript console?
https://code.sololearn.com/WA4GNuWfI8b0/?ref=app