I have no interest in lizards. Whatever their characters are, their appearance always frightens me.

frightens 是动词 frighten 的第三人称单数现在式。frighten 由名词 fright（惊吓、恐惧）加上动词后缀 -en 构成，意思是"使害怕、使惊吓"。在句中表示蜥蜴的外表总是让我感到害怕。