By Kelechi Wachuku
There are some features about Yoruba that stand out to me as interesting.
Yoruba has a phenomenon called vowel copying. This is most often realized with the third person singular object pronoun, which is simply a copy of the vowel of the preceding verb.
- Mo yí í = “I turn/turned it”
- Mo ra a = “I buy/bought it”
- Mo jẹ ẹ = “I eat/ate it”
- Ó fa a = “S/he/it pulls/pulled it”
- Ó sí í = “S/he/it pulls/pulled it”
This vowel copying also occurs as a clitic when showing emphasis, but is never the same tone as the previous vowel. 
- Ó lọ = “S/he/it went.”
- Ó lọ ọ̀ = “S/he/it went (emph).”
- Ó dé = “S/he/it arrived.”
- Ó dé è = “S/he/it arrived (emph).”
- Ó lé Akin = “ S/he/it pursued Akin.”
- Ó lé Akin ìn = “ S/he/it pursued Akin (emph).”
- Note: despite the “ -n” at the end of “Akin,” “-in” is “-ĩ” in IPA (a nasal vowel)
- Edit: You can see this in ordinary speech in this video below at 22:39:
Above: Yoruba Personal Pronouns
Consonant Deletion and Vowel Assimilation also often take place in fluent speech, which also takes tone into account, when certain consonants appear between two identical vowels or ones with similar points of articulation. 
- Òtító̩ → Òító̩ → Òótó̩ = “Truth”
- Erúrú → Eírú → Eérú = “Ashes”
- Èdídú → Èídú → Èédú = “Charcoal”
- Èrírí → Èírí → Èérí = “Dirt”
- Àrìrò → Àìrò → Ààrò = “Tripod Stand”
- Kúrò → Kúò → “Give way”
- Dúró → Dúó → “Wait/Stand”
- Dára → Dáa → “Good”
- Orí → Oí → “Head”
- Gò̩ púpò̩ → Gò̩ úpò̩ → Gò̩ó̩pò̩ → “Very stupid”
- Edit: An example of this can be seen the video below at 00:34. The examples aren’t the same as above, but are visible when seeing the tone assimilation of the assimilated vowel.
Above: Yoruba Greetings for Different Times of the Day
Yoruba, like many languages in West Africa, has labial-velar consonants, which, outside of this part of the world, is quite exceptional.
- Ogbon [IPA w/out tone:Oɡ͡bɔ̃] “wisdom” 
- Ìgbà (IPA: ìɡ͡bà)→ “period” 
- Pa [IPA w/out tone: k͡pa] → “kill”
- You can see an audio/visual example in this video below at 4:36:
Above: The Yoruba Language Alphabet & Tone Marks
Yoruba is a highly isolating language, much like Chinese. This stands somewhat in contrast to the languages in its broader linguistic family, which are often rather agglutinative.
- Ex: Olè fi ò̩bẹ gún ọba. (lit., “thief use knife stab chief/king”) = The thief stabbed the chief/king with a knife.” 
It also makes extensive use of serial verb constructions,too. In this case, verbs come right after each other without any other linking phoneme, like “to” or “and.” Also, there could be two or more verbs in the phrase that could just be translated as one verb in another language, like English. Lots of African languages have this feature, but is used to an extent that, for example, English or French speaker, are not used to.
- Ex 1: O mu iwe wa (lit., “he tookbook come”) = He brought the book [and came]. 
- Ex 2: Femi tì Akin subú (lit., “Femi push Akin fall”) = Femi pushed Akin down. 
Yoruba also has a fair deal of Arabic-derived words, such these below: 
“Àdúrà” → Prayer
“Àlàfíà” → Peace, to hail