In fact, teachers and professors give us the opportunity to broaden our knowledge, sharpen our critical thought and in general to cultivate our mind and soul.

sharpen 是动词 sharp（使锋利）的现在分词形式。sharp 本意是"锋利的"，引申为"使敏锐、使精进"的意思。 sharpen our critical thought 表示"磨练我们的批判性思维"，就像磨刀使刀刃更锋利一样，通过训练使思维更加敏锐。