Hi there, as stated above, the hearts are the love stat and used for breeding. The hover text for them can be turned off, you also have the choice to turn breeding off in the Breed section of the menu if you do not wish to breed your cats. Turning breed off will set the love stat to Off so the cats can not breed and the cats will also eat half as much food. (Note: if breed is turned off and you decide you want to breed the cat, then you will need to turn breed back on and there will be a 7 day cool down period before the cats can gain love again. Keep this in mind since the cats can only breed till day 120.)
You can also read all about stats here:
https://kittycats.ws/manual/article.php?id=8&oid=13
You can also read all about breeding here:
https://kittycats.ws/manual/article.php?id=60&oid=17
We hope this helps, if you have any other questions feel free to message me or submit a support ticket
