Literally, to complete the school work that has been assigned by a teacher to be done at home. You can't watch any more television until you do your homework! To be thoroughly prepared and informed about something or something, especially in advance of some process, action, or decision. Be sure you do your homework before heading into that meeting; there's a lot at stake, and no one's going to like it if you aren't up to speed.
An advertising team reading up on prospective clients they will soon meet is an example of homework. A math worksheet done after dinner is an example of homework. The speaker had certainly done his homework before delivering the lecture. You must do your homework before you can watch television.
In some subjects, like math, worksheets can be very helpful. It has to do with the value of practicing over and over. Educators have debated the merits of homework since the late 19th century. In recent years, amid concerns of some parents and teachers that children are being stressed out by too much homework, things have only gotten more fraught. She worries especially about socioeconomically disadvantaged students from low-performing schools who, according to research by Bempechat and others, get little or no homework.