What does it mean when the electric fan turns on the third gear?

Express the greatest love. This meme comes from a video shot by blogger Sun Xianyu. In this video, an old woman comes out of the house and shouts as she walks: "Ah, I won't let you go. There's not even an air conditioner. I'm too hot." "It's gone..." Then the grandpa also walked out of the house, trying to save the old grandma, and said: "Hey, don't leave, I will cool you down, and the fan will turn on the third gear." For the grandpa, the fan will turn on the third gear. It is the greatest love.