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You should be very happy that you're taking up more real estate in the SERP for a given keyword. They are of course "competing" - in the sense that every page in Google's index is being weighed to determine which is the best result for that query - but they aren't directly hindering each other.

The last thing you should do is remove a well-ranking page. If you would much prefer one page to rank higher than the other, then I would find ways to pass a little relevance from page B to page A, such is with an internal link or additional optimization. Otherwise, remember that total clicks to 2 pages ranking lower on the page may very well be equal to or even exceed clicks to a single page that ranks higher.

If you're using the Yoast WordPress SEO plugin (which is the best for SEO, in my opinion), and you go under Permalinks within the SEO menu, the first item on the list is the option to "Strip the category base (usually /category/) from the category URL."

If you do this, I would of course first compile a list of your current category URLs and all the URLs that live under them, and drop them into whatever you use for 301 redirects (I use a plugin called Redirection, which is great) and redirect everything on that list to the version of that URL without the /category/.

It is the average monthly exact match search volume. If you're using the tool, hover over the question mark beside "Avg. monthly searches" in the table and you'll see the full description of the data:

The average number of times people have searched for this exact keyword based on the targeting settings that you've selected.

About the number: We calculate the 12-month average of the number of searches for this exact keyword based on the location and Search Network targeting settings that you've selected (not including your language setting).

How to use it: See how popular this keyword is. This information can give you an idea if adding the keyword to your campaign will help you reach your advertising goals.

Note: If we don't have enough data, you'll see a dash (-). Average monthly searches don't take into account the keyword match types you've selected. To see the traffic for different match types, look at your click and cost estimates on the review page.