As an English speaker I would translate this sentence as, "We see good fruit" (as in, "we see good fruit over there", pointing at the fruit), or more correctly "We can see good fruit". It would also be correct to say, "We can see the good fruit" as opposed to the bad fruit. However, you would never say "fruits" as has already been explained previously.
Which is really more natural here – we rather rarely use „widzimy” with objects outside of 1)questions 2)tour guides, so „Widzimy dobre owoce” is something I would expect to be said by a tour guide to botanical garden trip.
In fact, language like that was always my major annoyance with guided tours/trips – my immediate reaction to something like „Po prawej widzimy Ołtarz z 15 wieku wykonany przez ucznia […]” is wish to answer with „Nie, nie widzimy, bo akurat nie patrzymy w tym kierunku”. :P
I would(and most of my friends too) say: „Po prawej możemy zobaczyć […]” and I think it's actually some kind of stylistic rule in Polish, but not sure.
In British English, at least, using fruit as a mass noun is more usual and correct, but using it as if it's countable is becoming more common, and it's my impression that it's more common in American English. In my experience, at least, it's really not particularly unusual for an American to say fruits in a situation where, as a Brit, I would certainly say fruit.
And there are occasions when fruits is grammatically correct even in British, absolutely fundamentally correct English.
At any rate, as long as "we see good fruit" is also accepted (which it should be, by this point, I'm sure it's been reported), then I don't see it as a huge problem.