Онҳо даҳ дона китоб оварданд.
They brought ten books. Дарс соати даҳ тамом мешавад.
The lesson ends at ten 0’clock.
Learn the numbers from 1 to 100 on this Tajik Wikipedia page: Шумораҳои ҳисобӣ
The word дона (unit, piece) is a special word, called a classifier, that is used with numbers. Classifiers are often left out when translating into English. Read more about how to use them in this post – дона.