Phrase mentioned/shown at the end of various Japanese Anime (such as at the end of Gundam Wing, and Cowboy Bebop right before the next episode preview.

Jikai is represented by two kanji, Ji 「次」, and Kai 「回」.

Ji defines the next item in a sequence, and the character Kai is a Japanese Counter for the number of occurances.

When spoken (or read) as "Jikai" it's meant in the sense of "next time."

The full phrase, jikaiyokoku 「次回予告」, basically means "preview of the next episode".