The improvement in her language skills was quite noticeable after she spent a year abroad.

noticeable 是由动词 notice（注意到）加上形容词后缀 -able 构成的形容词，表示"可以注意到的、明显的"。-able 后缀表示"能够...的"，所以 noticeable 字面意思是"能够被注意到的"。