Learn Turkish: O köpek küçük, korkma. - That dog is small, do not be afraid.

The root of the verb is kork- (from korkmak, to be afraid). To tell someone not to do something, you add the negative suffix -ma or -me directly to the root. Because kork- has the back vowel o, vowel harmony dictates we use -ma.

Where is the voice stress placed when saying korkma?

In Turkish negative commands, the stress falls on the syllable just before the negative suffix. So, you should emphasize the root: KORK-ma.

Doesn't O mean 'he', 'she', or 'it'? Why does it mean 'that' here?

Yes, O is the personal pronoun for 'he', 'she', or 'it'. However, when you put it directly in front of a noun (like köpek), it acts as a pointing word (demonstrative adjective) meaning 'that'. So, O köpek means 'That dog'.

Why is there no word for 'is' after küçük?

In Turkish, simple descriptions don't always need a visible 'to be' verb. For the third person (he, she, it, or 'that dog'), just stating the adjective küçük is enough to mean 'is small'.