Changing language of some titles

Hi there,

Just wondering why I have some words in English and some in another language see screenshot, how can I change all this too English only.

https://i153.photobucket.com/albums/s227/Black_Ball/screenshot_zpsd203debc.png

Thanks for any support in advance.

https://www.ads-software.com/extend/plugins/wp-fullcalendar/