Well this all depends what you are looking at, but if you have something living then what you can probably see are cells.
What’s a Cell?
What are you made of? Here is a picture of some cells. Each red and green blob is one living cell (from your pancreas), these cells make insulin – you can see the packages of insulin in the tiny red dots inside the cells.
Sometimes you can see individual cells – like pollen grains. Pollen is the stuff that causes hay-fever – some people are allergic to pollen cells and their body thinks they are germs. When the body attacks germs, it can make you fell bad. That’s what causes hay-fever. Pollen looks like fine dust but each grain is a single cell about 1/10th of a millimetre across, so you can just see them with your naked eye. We call your eyes without any help from a microscope, or telescope, the naked eye.
Cells are all different shapes and sizes depending on their job.
Here are some nerves cells – long and thin because they might need to stretch from your spinal cord in your back to your big toe – so these can be 1 metre long (but very, very thin)