If you condone something, you allow it, approve of it, or at least can live with it. Some teachers condone chewing gum, and some don't.
Things that are condoned are allowed, even if everyone isn't exactly thrilled about it. People often say, "I don't condone what he did, but I understand it." Condoning is like excusing something. People seem to talk more about things they don't condone than things they do condone. Your mom might say, "I don't condone you staying up till 10, but I know you need to read." That's a way of giving approval and not giving approval at the same time.