I can't Install and Update Plugins from my site and Getting this errors

Can you give us some more details? Were you setting up WP for the first time, or updating WP? What happened right before you got this message– for instance, were you installing a new theme or plugin? Not much to go on here…

I want To Install Plugins From My Wp Dashbosrd >Plugins>Add New.
But There Was Showing This Error.

An unexpected error occurred. Something may be wrong with www.remarpro.com or this server’s configuration. If you continue to have problems, please try the support forums.

Warning: An unexpected error occurred. Something may be wrong with www.remarpro.com or this server’s configuration. If you continue to have problems, please try the support forums. (WordPress could not establish a secure connection to www.remarpro.com. Please contact your server administrator.) in /home/mysite/public_html/wp-admin/includes/plugin-install.php on line 83

WordPress Versions : 4.3

My Site Hosted On Hostjagat.com.
Apache Version 2.4.12
PHP Version 5.4.42
MySQL Version 5.5.42-cll
Architecture x86_64
Operating System linux
cPanel Pro 1.0 (RC1)

Have you tried deactivating all your plugins to see if this resolves the issue? Sometimes, a plugin might create a conflict. Likewise, a theme can do this too– if you have recently changed your theme, you might temporarily go back to a default theme to test.

If neither of these work, you could try changing WP_DEBUG to true in wp-config.php and see if there is any more info you get.