What a minor pentatonic scale is
Minor pentatonic uses scale degrees 1, flat 3, 4, 5, and flat 7. In A, that is A, C, D, E, and G.
The missing 2 and flat 6 keep the scale focused. The flat 3 and flat 7 create the familiar minor pentatonic color heard in blues, rock, folk, and many singer-songwriter styles.