Text when posting to facebook

When I post my URL (www.scienceworkstv.com) in a facebook post, the following text appears - Welcome to your site! This is your homepage, which is what most visitors will see when they come to your site for the first time. Here is an screenshot - https://www.dropbox.com/s/xf95w2a8npl0fg9/Screen%20Shot%202017-06-03%20at%207.20.06%20PM.png?dl=0

I want to know how to change this text

Hello there,

To replace the default text, you’ll need to use an extra plugin to insert your text to the open graph meta description; there is nothing to with the theme actually. Here is the plugin worth it to try.

Regards,
Kharis