It means to refuse to face or acknowledge a problem by pretending not to see it. This expression, transferred to human behavior in the early 1600s, alludes to the supposed habit of ostriches to bury their heads in sand when faced with attack by predators. But ostriches don't hide, although they do sometimes lie on the ground to make themselves inconspicuous. This phrase is likely to have originated from people observing the ostriches lowering their heads when feeding.

Übersetzung:

den Kopf in den Sand stecken

Gegenteil(e)

The opposite of "bury one's head in the sand" is "to face a problem".

Synonym(e):

You could also say: to refuse to confront a problem.