"Judo (Japanese for “the gentle way”) emphasizes winning in combat by using your opponent's weight and strength as weapons against him, while preserving your own mental and physical energy."
Using your opponents strength as weapon means deflecting their attack and using the force to throw them on the ground/defeat them.
Have a look at e.g. 5:58 https://youtu.be/-Qe_JKQjJTA It’s kata, so slow and meant for demonstration purposes.