WHOLE CHARACTER
买mǎi
to buy; to purchase; to bring on oneself (买祸)
买 is to buy — trading money for things; the simplified shape is taught whole, since the older pieces are gone.
ZDIC marks the formation as originally 会意 for the older 買; the simplified form keeps no readable trace of those pieces, so the modern split is a visual aid only.
TOP HOOK-COVER STROKE PIECE
乛
Notice this part of the shape; it is not taught as a separate word in this lesson.
In 买: top hook-cover stroke piece A stroke-shaped top piece with no claimed meaning.
头-SHAPED LOWER PIECE
头tóu
head
Shown as the lower piece in 买 as a visual aid only; the historical account belongs to the older 買.
In 买: 头-shaped lower piece Shown as a visual memory aid; the standalone meaning of 头 is not claimed here.