What is this j for?

Question

I’m a new learner. can anyone please help me why the answer is 5.0 for the following?( sorry for the silly question). Thanks in advance

Print(abs(3+4j))

Answer 1

abs() shows the absolute distance from the 0 point, for complex numbers, too.

Please refer to this post below:
https://www.sololearn.com/Discuss/2209933/?ref=app