Ancient Delos was a center of regional trade. The inscription, the top half of it, is written in the Minaean language of Ancient Yemen. The Minaean people were a mercantile people who'd travel afar to trade their precious incense. The inscription, apparently left by traders, reads:
Hāni' and Zayd'il of the tribe of Hab erected the altar of Wadd and of the deities of Ma'in at Delos.
South Arabian is a grouping of the Semitic languages and of a distinct branch of the Phoenician-style alphabet. It's distinct from Arabic.
Minaeans in the Mediterranean. Reevaluating two Old South Arabian inscriptions from Delos
by Bnedem