This time is made up of the socket connection time the time taken to send the HTTP request and the time taken to get the first byte of the page.
Each time you ask for a website page or blog post that is uncached the server will need to process the PHP files in question to convert them in HTML format back to your browser.
You can see that a bad Time to First Byte will mean that the reader will have a situation similar to a gamer connected to a poor server.
The faster the CPU and the more resources your hosting allocates to you the faster it will process those files and hence your TTFB will be smaller..
Also if your hosting implements a PHP caching this will be further reduced on the second request as it will provide a cached version of that file instead of having to process the PHP file all over again..
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