Translation:The children are eating fruit.
Is "Children eating fruit." a possible translation?
"Children eating fruit" would be "Dzieci jedzące owoce". Here you put emphasis on the children more and use what they are doing as their description.
In "children eat fruit" or "children are eating fruit" you are pointing out what the children are actually doing.
If you mean "Children eat fruit" than yes.
It seems "owoce" is plural. How would it be ·"A fruit"?
However, we wouldn't say "a fruit" here. In English, "fruit' is generally uncountable. We could say "some fruit", or more often we'd probably simply specify, e.g. "an apple".