You can apply such emojis in electronic devices to illustrate love and affection. Hearts instead of eyes or other face parts express love or falling in love. A mouth shaped as a heart and turned 90 degrees counter-clock wise (w) symbols a kiss. Squinted eyes signal that the person is moved and touched. Red cheeks speak of shyness.
I don't know why, but looking at these emojis, I recalled the following meme: