"It is a turtle."
Translation:O bir kaplumbağa.
Thekla, there are no teachers here!!!! Learners help each other. I am a learner and help the others with what i understand of the Turkish language and its grammar. But i work hard on my own, looking for websites, etc. And I read all the comments for each new sentence. I take notes, etc..
In "O bir kaplumbaga", "O" is a personal pronoun, singular, subject: "it", before the verb "is". "O" as personal pronoun, subject means: it, she, he and as a demonstrative pronoun: that (singular) and those (plural). You employ "onu" for example: in "onu yerim" = "i eat that", demonstrative pronoun, object= it, him, her. "Onu" is the accusative form of "o": "o"+"nu" (suffix). Have a look there: "turkish grammar portal" duolingo forum.
Mohammad, "it" in the English sentence here is a personal pronoun at third person singular, subject of the verb "is". But "o" can be a demonstrative adjective meaning "that" before a noun as in "that turtle is green" and a demonstrative pronoun as in "that is a turtle"="o bir kaplubaga" with an idea of distance. Have a look there: https://elon.io/learn-turkish/lesson/demonstratives and. Not complete but clear.
Fadima, the same. I find this website about pronouns: https://en.wikibooks.org/wiki/Turkish/Pronouns#Demonstrative_Pronouns. Selcen did a table in Duolingo Turkish Grammar Portable, topic pronouns.