两面 can refer literally to the two sides of an object (e.g., paper, a coin) or metaphorically to both aspects of a situation or issue. In a negative context, it can also mean 'duplicity' or 'two-facedness' — describing someone who speaks or acts differently in different situations. As a noun, it often appears in phrases like 两面性 (dual nature) or 两面派 (two-faced person).