Hey, thank you for the great explanation! However, I still find it difficult to understand the meaning of the expression ''reflect off (something)''. I shall write a few sentences below, and I would really appreciate it if you could tell me whether they are correct or not.
1. She let out a very loud shout that it reflected off the cave walls.
2. By drawing near the water, you may see your image being reflected off its surface.
3. All those lights reflected off the mirror on the wall.
4. To run this experiment, you must know this: When you own a flammable tinder (such as a piece of cloth or a sheet of paper), you should use the magnifying glass to concentrate the sun's heat onto the tinder, and the sunlight that can reflect off of its lens, shall soon spark a fire.
*Notice: The fourth sentence may be wrong, but I just wanted to explain the usage of a magnifying glass to create fire by using the expression ''reflect off'' in the context.