In the Mbeya-Iringa cluster, one of the objectives is to create a dictionary for each of the ten languages.

Publishing a dictionary will give status to each language; it shows that the people speak a ‘real' language. It also helps the community with spelling—they have no literary history to build upon—and with using English and Swahili, which is the language of wider communication. Therefore, three language (triglot) dictionaries are being developed. 

Cooking on mafiga 'cooking stones' has a
a wide range of various terms to include
in a dictionary (Tanzania)

When translating the Bible, translators use the common local language to explain abstract concepts, even using phrases to convey the meaning of a word. If as people  read the Bible they can look up unfamiliar words in a dictionary then they will gain a deeper understanding.  

A dictionary doesn't just help mother-tongue speakers, it also helps language learners. It is amazing how much anthropology can be learned simply by reading a dictionary. For example, the Malila language has many words associated with beekeeping, showing the local importance of honey. And finding the English or scientific names for these important domains is a challenge. But a good dictionary provides that information.

Dictionaries help native speakers as they learn to read, they help language learners, and they also help anthropologists and linguists to understand a language and a people better, like those that consider some rodents a delicacy.