What are crawl stats ?
Crawl Stats in google webmaster tools give you a high level overview of Google's crawling process and in other word that describes the process of collecting data on the website of the search engine bots.
Crawling is the process by which Googlebot discovers new and updated pages to be added to the Google index. We use a huge set of computers to fetch (or "crawl") billions of pages on the web. The program that does the fetching is called Googlebot (also known as a robot, bot, or spider).
Crawl Stats is showing Googlebot's (Google's search engine robot) activity.
Crawl stats allow us to see
How many pages Google crawls per day
We can monitor if Google are able to access pages on your site.
Hoe many kilobytes Google downloads per day
We can monitor how much data Google has downloaded.
How much time Google spent to download a page
Google's ability to fetch and crawl web pages is incredibly fast and efficient, the crawl stats provides insights for "Pages crawled per day" "Kilobytes downloaded per day" and also "Time spent downloading a page (in milliseconds)" and all these statistics are important to view and understand especially if your website.