"Her ovens are big."
Translation:Cuptoarele sale sunt mari.
Nothing special here. The adjectives have in general 4 forms as they have to be in accordance with the noun (masc sg / fem sg / masc pl / fem pl) Example: bun / bună / buni / bune. Some adjectives are though less complicated because they have the same form for masc. and fem. , therefore only 2 possible forms remain (sg / pl). This is the case of mare (masc. or fem sg.)/ mari (masc. or fem pl.) Similar to other adjectives ending in ”e” (tare / tari; rece / reci; limpede / limpezi; iute / iuți; fierbinte / fierbinți; etc.)