Once you master the language quite well, listening to a news broadcast is a refreshing challenge that may require some serious concentration on your behalf.

refreshing 是形容词，由动词 refresh（使恢复活力）加后缀 -ing 构成。refresh 由前缀 re-（表示"重新"）和 fresh（新鲜的）组成，字面意思是"重新变得新鲜"。refreshing 引申为"令人耳目一新的、使人精神振奋的"，形容能带来新鲜感和活力的事物。