Dynamics in music is like the loudness and softness of the sound that you hear. When you listen to music, you notice that sometimes it's really loud and other times it's quiet. This is called dynamics.
Dynamics are like the ups and downs of a roller coaster. When the music is loud, it's like going up the hill of the roller coaster, and when it's soft, it's like going down the hill.
Musicians use different symbols to show the dynamics in the music. A letter "p" means "piano," which is Italian for soft, and a letter "f" means "forte," which is Italian for loud.
Sometimes there are even more letters to show how the dynamics should change during the song. For example, "mp" means "mezzo-piano," which is medium soft, and "ff" means "fortissimo," which is very loud.
Dynamics add emotion and excitement to music, just like the ups and downs of a roller coaster make it more fun. Next time you listen to your favorite song, pay attention to how the dynamics change throughout the song.