They are in the game and mostly found around the Great Fairy Fountains. When Link dies it’ll restore 5 hearts and bring him back to life.
The 4 Great Fairy Fountains can be found in various places threw out the game. The fairies will can be found around the pods that the Great Fairies are in.
You can also cook them in a meal and make a Fairy Tonic to give you more hearts. If you do make a Fairy Tonic keep in mind that if you die it will not bring you back to life so keep an eye on your hearts.
I hope this helps. Also it’s not a problem. That’s what we’re here for! ^-^
I am getting increasingly worried about how much my game is crashing these days whenever I try and use a settlement that I’ve spent so long building up, so I think my next few posts are going to be dedicated to each of my settlements, just so I have an organised record of how they looked when I was really happy with them. So if my files become corrupted, which I think they will, I will have an archive. But be warned they are going to be quite long posts, mostly for my own memory of what they look like