The "began" is used to indicate that an action or event started or commenced in the past. It signifies the start of something and is the past form of "begin". To form the past tense, we change the base form "begin" to "began". This change in spelling signifies that the action happened at a previous point in time.
When we use the past tense of "begin", we are referring to an action that started in the past and has now been completed or is no longer occurring. It is an essential grammar concept in both English and Chinese, allowing us to express events or actions that happened before the present moment.