What one is taught, or also the manner in which one is taught.
general terms, one is taught by instruction or by example, and one is taught
by one's parents and family; in one's place of work; and in special social
institutions, normally called schools or universities. What one acquires when
one is taught are generally beliefs and values.
It should be noted that it takes some fourteen to twenty years to educate a
human being to the extent that he or she
is capable of functioning more or less properly in
society, and to play the common
roles in it (as of: citizen, man, woman, doctor,
lawyer, milkman, nurse).
There is a pseudoscience of education, called pedagogy: I call it a pseudoscience (i) because what I have read of it generally is ill-written ideology rathter than science and (ii) because there is nothing in the way of rational theory with empirical support that explains how the human brain learns (other than in trivial ways on trivial tasks).
One reason to add this explicitly is that the standard fare of school education, if not harmful for children in general, is certainly harmful for gifted children.