"You are not weak, you are strong."

Translation: Voi nu sunteți slabi, voi sunteți puternici.

[jansooi]

in English "you are" does not necessarily indicate a plural though

[KevinSmith777042]

You are right there - it can be singular (tu esți) or plural (voi sunteți) but in Romanian the adjectives must agree in number with the subject.

[RichardMax19]

How do I know that the sentence is plural or singular? English does not make that difference? You might want to add some clues to distinguish the form you want us to use or give the two options.

[bio7899]

Does slabi also mean weak?

[razvan.marin]

Yes!

[Taid997114]

I also do not see anything to indicate gender, so could be "slabe" and "puternice" - or did I miss something earlier about this?

[Alfredo718461]

Hi. I think it is also a correct answer to say: "Du nu esți slabi, Du esți puternici". Isn't It?

[KevinSmith777042]

No: esți is singular, puternici is plural.
What is Du? I haven't met it in Romanian - do you mean Tu?
DL does also accept the singular version but it took me 3 goes to be consistent and not make mistakes like putting 'ti esți slab'!