Cola nuts have a sweet, floral (but mild) aroma, but the taste is bitter although this sweetens upon chewing. Cola Nuts do contain caffeine.
Cola nuts are eaten in West Africa as follows: by breaking them open, cut them into pieces, then chewing the pieces like chewing gum then spitting out the fibrous material. Most people find the taste very bitter, especially at first. The stimulative effect is similar to a strong cup of coffee and it used to be carried around and eaten to keep people going when out and about.
Kola is used to flavour cola drinks. Law's Grocers Manual which says "Kola, combined with coca (or koka), a shrub native to South America, whose leaves are rich in stimulating alkaloids of a different nature from those found in kola, is much used in an effervescent drink extremely popular in the United States of America and Canada called Coca-Cola" - you don't say!