Bod - That
bod is, of course, the Welsh verb 'to be'. Under certain circumstances it also means 'that'.
bod is used to introduce noun clauses
e.g. Dwi'n gwybod - I know and Mae Dai yn feddw - Dai is drunk.
If we combine the two we use 'that' In English and 'bod' in Welsh:
Dwi'n gwybod bod Dai yn feddw. - I know that Dai is drunk.
Although 'that' can be omitted from English sentences ( e.g. "I know Dai is drunk") bod should always be included in Welsh.