Answer:
Your topic is the subject of your essay or paragraph. You should choose a topic that is interesting to you, because that way you will have an easier time doing your report.
If you're not sure what topic to choose, do a search online for the general subject, and see what kinds of topics come up underneath that general heading - you want something that is specific enough for you to be able to write a short report about.
For example: "Animals" is a very broad topic - you would need to write a whole book to talk about all the different animals! "My dog" is a very specific topic, and you could easily write a short essay or paragraph about that!