That is a billboard in Dallas guard J.J. Barea’s native Puerto Rico. The statement on it (via The Basketball Jones, via Bethlehem Shoals), translates to “Only my ribs hurt, but for Kobe, it’s his ego.”
When the Mavericks were leading by 30 in the final quarter of the final game of a sweep of the Lakers, Barea was laid out while making a floater by a brutal hit from the Lakers’ Andrew Bynum, who was suspended from the foul. Considering the “ribs” comment, the billboard seems to be a reference to that specific moment, with Kobe switched in for Bynum because of name recognition purposes. Bynum was suspended for the hit, but for Barea, this billboard is a pretty sweet way to get back at the Lakers for the needless cheap shot they took at him. It’s entirely possible that Carlisle decided to start Barea over Stevenson in Game 4 solely because he was made aware of this billboard.