ești - second person singular
sunt - either first person singular or third person plural
Romanian grammar is tough, at least for this English speaker. Mersi for the info!
Tu eşti = You are. In romanian you can omit the "tu (you)" as it is implied by the form of the verb: Eşti frumoasă = You are beautiful. El / Ea este = He / She is. "E" is short for "Este" (100% equivalent). El e bun = El este bun = He is good.
I lost about ten minutes in my answer and the formatting ruined it!! :) Here https://www.duolingo.com/skill/ro/Basics-1 You find the verb a fi - to be (down the page) In Romanian the verb changes with all pronouns... that why you don't need to always say the pronoun: if you say esți, we know it is you; if you say este, we know it is s/he.
danix_93, our error is not in Romanian... :) it's in English, I think.. you don't need the second tu (you) in Romanian, but in English yes... Or the phrase is wrong in Romanian!! :)
There are indefinite articles that are separate and go before the noun, but also definite articles that attach to the end of the end of a noun.
This is like Spanish when we want to get to the point, "Usted/Tu no es hombre, eres varon".