How do I fix this error

That looks like an error in a plugin called “Slider”. You can test by disabling that plugin and seeing if the error re-occurs.

Note that this is not the place for plugin error/support. You should use the plugin’s support forum.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)