I'd like to share AvE's video[0] here of a tear down of an AoA sensor. It's really quite interesting. More info on the AoA sensor's role in the Wiki entry[1].
TLDR/TLDW: AoA sensor measures "angle of attack." AoA sensors are physically over-engineered, but the electrical components may be questionable. If an AoA sensor fails, it may cause a stall. The 737 Max is equipped with two sensors, however, effectively utilized only one at a time because it cost extra for the "AOA-disagree" feature.
[0] https://www.youtube.com/watch?v=NhZ0D-JRtz0
[1] https://en.wikipedia.org/wiki/Boeing_737_MAX#Maneuvering_Cha...
TLDR/TLDW: AoA sensor measures "angle of attack." AoA sensors are physically over-engineered, but the electrical components may be questionable. If an AoA sensor fails, it may cause a stall. The 737 Max is equipped with two sensors, however, effectively utilized only one at a time because it cost extra for the "AOA-disagree" feature.