1. 课程；一堂课
    A lesson is a fixed period of time when people are taught about a particular subject or taught how to do something.

    e.g. It would be his last French lesson for months...
           这将是他以后几个月里的最后一堂法语课。
    e.g. Johanna took piano lessons.
           约翰娜上了钢琴课。

2. 教训；经验
    You use lesson to refer to an experience which acts as a warning to you or an example from which you should learn.

lesson在线翻译

    e.g. There's still one lesson to be learned from the crisis—we all need to better understand the thinking of the other side.
           从这次危机中我们还可以吸取一个教训——我们都需要更好地了解对方的想法。

3. （教堂礼拜中的）《圣经》选读
    In a church service, the lesson is a short piece of text which is read aloud from the bible.

    e.g. The Rev. Nicola Judd read the lesson.
           尼古拉·贾德牧师选读了经文。