There are a couple of theories as to why we use the word “love” to mean 0 points in Tennis.
Here are the two most convincing:
1) By far the most popular theory is that the word ‘love’ comes from the French word ‘l’oeuf’ which means egg.
This is because the number 0 looks kind of like an egg.
2) Another theory is that the word love is used to mean no points because love for the game is the only reason a player with no points would continue playing.
He loves tennis so much that he will continue, even though he is losing.