Who is Grace Makutsi from The No. 1 Ladies' Detective Agency and what is their importance?

Grace Makutsi, recently widowed and a recent graduate from secretarial college, is hired by Mma Ramotswe to work as a secretary/assistant in the No. 1 Ladies' Detective Agency. Efficient and quiet, she plays a relatively minor role in this first book of the series, but plays an increasingly important role in later books.