Keywords Everywhere is a browser addon that has the following functionality
Get monthly search volume, cost per click and competition data for your list of keywords. You can copy keywords directly from Excel and download them as an Excel, CSV or PDF file. Select any set of words on any website and right click to get the keyword data for the selected words
You are able to view keyword search volume, cost per click and competition data, on many websites like Google Analytics, Google Webmaster Tools (now called Search Console), Ubersuggest, Majestic and Moz Open Site Explorer.
What do Search Volume, CPC and Competition mean?
Search Volume: This is an average of the total searches that people have performed for this keyword per month over the last 12 months. For e.g. a search volume of 1000 means that people have searched for this keyword an average of 1000 times every month for the last 12 months.
CPC: The cost per click (CPC) is the amount that advertisers are paying for a single click for this keyword in Google adwords.
Competition: The competition is a gauge of the number of advertisers that are running ads on Google adwords for this specific keyword. The number goes from 0 to 1, with lower values signifying less number of advertisers and higher values signifying more advertisers.