Explanation (i.e. ruining the joke)
There is a traditional Jewish song often sung at Sabbath meals, the chorus of which contains the line “Yona matzʾa bo manoʾaḥ”—“A dove found rest in it [the Sabbath].” This is an allusion to Genesis 8:9, wherein a dove sent out by Noah during the flood couldn't find a place to rest.
The word for “dove” is Yona, the same as the name of the biblical prophet Jonah, who was temporarily swallowed by a large fish. In Modern Hebrew, the word manoʾaʿ means “engine” and sounds like manoʾaḥ (rest).
Hence the play on words: “Yona matza bo manoʾaʿ”—“Jonah found an engine in it,” as illustrated above.