robot.txt on google search

when I search on google, I will write "juallagu.com", after that I get this sentence " plg_gkextmenu - Mainbody Tab 2
juallagu.com/plugins/system/plg_gkextmenu/‎
A description for this result is not available because of this site's robots.txt – learn more."

I don't understand what happen

Please give me a solution about that

Hello,

The only result which I've found in Google for the mentioned phrase and containing the mentioned sentence is a link to this topic