"The man eats the strawberry."
Translation:Itheann an fear an sú talún.
There are three sú words in Irish; two of them are masculine, and one of them is feminine. The masculine ones mean “juice” and “absorption” respectively; the feminine one means “berry”. Since this exercise is asking for a translation of “the strawberry”, the feminine sú is the proper one to use. Since it is feminine, the translation above should be an tsú talún rather than an *sú talún.
Groundnut is a similar word in US English, if that helps.
It's the same as the difference between "el" and "los" in Spanish.
An is "the" for singular nouns, na is "the" for plural nouns. Unlike Spanish, definite articles in Irish are not gendered in the nominative case.
an díon - "the roof" - "el tejado"
na díonta - "the roofs" - "los los tejados"
an fhuinneog - "the window" - "la ventana"
na fuinneoga - "the windows" - "las ventanas"
(Note that fuinneog is a feminine in Irish, so it is lenited after an).