This is an inscribed sun-dried brick used in temple construction. It was commissioned by the Sumerian king Amar-Suen (reigned c. 2094-2038 BCE) of the Third Dynasty of Ur.
Translation of the inscription:
Amar-Suen, the one called by (the god) Enlil in (the town) Nippur,
supporter of the temple of Enlil,
the strong king,
king of Ur,
king of the four (world) quarters,
for (the god) Enki
his beloved lord,
he (i.e., Amar-Suen) built his (i.e, Enki’s) beloved (temple) Abzu.