Is this the wp-post table or wp_posts? In the latter case, your site is WordPress based and someone must have been able to add or access an account on your site with enough rights to publish new posts.

First you have to upgrade the CMS and the plugins to the newest versions to plug possible security holes.
Next step is to change the system settings to prevent new accounts with posting privileges to be created.
Then remove all posts which you don't want on the system. Best is to do this through the interface of the CMS, not directly in the database. Often multiple tables have to be changed and the only safe way to do that is by letting the application do it for you.
When all unwanted posts have been deleted, monitor the system carefully to see if new unwanted users are created or new posts emerge.

And last but not least, change the passwords of your account (CMS, hosting etc) to something new.

Quick reply: there is no any published, draft or trash article on backend. There isn't any user acc, only 2-3 that I created, no more
There only one such table in wp, I'm not sure its wp_post or wp_post, but that's the only default table for post and pages.

It looks like automated attempts (failed scripted posts) at posting spam. Is it possible that Akismet (anti-spam plugin) stores these posts? If they are in the database, something is adding them. Is is possible to determine a time-stamp from any of the entries and match it up with access logs? That might show you how/where it is coming from at least.

That was Flamingo message storage plugin, which use wp_posts plugin and there was >10K messages. All messages removed, list of blacklist words installed. Thanks not2easy for directing in right direction (akisment/flamingo, etc :)

I'm glad you could find the source of it. Even if it doesn't show, it adds to your database overhead.