"What are pockets of calm?" (I changed "is" to "are" because pockets is plural; is works with singular nouns and are works with plural nouns.) Pockets of calm or brief periods of time when things are calm during an otherwise noisy or chaotic time. They can also be a small space that is quiet in an area that is noisy or chaotic. So if there was a loud storm outside, but it stopped being noisy for a minute or two and then started to be noisy again, that calm minute or two would be a "pocket of calm." Or, if there was a lot of noise at your work but you had found a certain small room that was quiet, that would be a "pocket of calm."

pockets of = lots of