To broaden one's horizon means to expand one's knowledge and understanding of the world. This expression comes from the metaphor of a horizon as the limit of one's knowledge and understanding. Here are some examples:

Reading books and traveling are great ways to broaden your horizon.

She attended a conference in another city to broaden her horizon and learn from experts in her field.

Through his experiences abroad, he was able to broaden his horizon and see the world from a new perspective.

In Chinese, we can say:

阅读书籍和旅游是开阔视野的好方法。

她参加了另一个城市的一个会议，以开阔她的视野，并向同行业的专家学习。

通过他海外的经历，他能够开阔视野，从新的视角看世界。