They show a Hebrew letter progression/equation from "Yeshu" (Jesus) to "Yeshu'a" (Salvation) with a web address which is a proselytizing, missionary website.
These billboards are illegal as missionary activity in Israel is forbidden under law, and they outraged many. Some of the billboards were defaced.
Under intense public pressure, the Keshet advertising company took down all the signs and replaced them with a huge apology:
Dear Residents of Lod
We apologize for the anguish caused by the ad campaign which attacked your sensitivities. May G-d be with you and send you blessings, success, economic wealth, and prosperity.
With blessings for a plesant and enjoyable summer.
hat-tip: the Luddite and rotter.
Wherever I am, my blog turns towards Eretz Yisrael טובה הארץ מאד מאד