A Window
Windows can be a lot of different things, and can also represent a lot of different things. There are literal windows, like the ones you see through each morning as you wake up, and then there are abstract windows. Abstract windows are objects or ideas that represent windows, like knowledge.
Having a good education and a wide knowledge is an extremely important part of life, and makes you useful to the people you work with. Education is not necessarily mandatory in life, but with education you will live a better life, because you can do almost anything you want and be successful.
Like a window in which you can see out of into other parts of the world, having a good education is like seeing out of a window into the options of jobs you can have in later life. You can get a job that you like and have a life that you like. Without a good education, you don't have a lot of options.
It is as if the window was almost closed all the way and you could only see out of a crack. You cannot see all that you want and like, but you really want to see everything. However, the window is only opened that much and it cannot be opened any more because you cannot change your past. You will be limited to only some jobs, and they might not be the ones that you like. It is already too late to start learning more things, so you have to stick to the limits. The window cannot be opened more. It could only be opened in early life. When you finally realize that you need to have a good education, it will be too late. This is why you need a good education early on in life.
Open the window to its fullest while there is the opportunity, before it is too late.