"Tamer is smart."
English transliterations for names frequently change with vowels. So, essentially Tamir and Tamer are the same, even though to be precise, Arabic has no "e" vowel in normal speech. Anyway, there are some names that are transliterated in specific way in English by convention rather than by precision of pronunciation.
It's not زكي. It's ذكي.
Typically Egyptians (and few others, because of their dialect) do mix these sounds and often write the proper name Zakiy زكي as δakiy ذكي [I'm using the Greek letter "δ" here for TH sound as in "This" in English].
The change in sound changes the whole meaning:
- Zakiy زكي: Purified.
- δakiy ذكي: Smart.
Among other sounds that they mix up as well is (s: س) and (θ: ث). Their dialect affects their proper Arabic a big deal that often they miss out the spelling of many words containing these sounds that they change its pronunciation in the dialect. Just noting this down in case you are learning outside of Duolingo from resources that probably teach a dialect rather than Arabic (and they keep calling it Arabic).