Google Keyword Noob Question

I've tried searching the forums, but I can't seem to find any explanations, just more references.

I was enjoying #4 spot for my main keyword (with over 25 million competitors and 90K exact monthly search volume)

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This sentence (Credit to jr_sci) basically embodies my question being what does this all mean?

Are there any intros to the Google Keyword Tool out there? Could someone basically break down the quoted sentence into what this all means and how to check it?

Thanks!