A Asus2 chord contains the notes A, E, B. It is built from the suspended 2nd formula 1 - 2 - 5, with A as the root.
What is the difference between Asus2 and Asus4?
Both remove the major third, so neither is major or minor. Asus2 replaces it with the second (B), which floats gently above the root; Asus4 uses the fourth (D), which sits higher and pulls harder toward resolution. Sus2 is the calmer, more open-sounding of the two.