Dobro writes the consonant d and takes the numeral five. Its name is the Slavonic word for good, used as a noun, and it carries the recited sentence forward: after glagoli comes dobro, and the two words with the one that follows make a clause about speech being a good thing.
The letter records a plain dental stop, and Old Church Slavonic uses it heavily. It stands at the head of a large class of verb forms, and it takes part in several of the consonant alternations that the language inherited, so a reader meets it both as a stable consonant and as the sound that changes when a suffix is added. Manuscripts of the canon are consistent in writing it, which makes it one of the letters least useful for dating or placing a text.
Its numeral value follows the Glagolitic system of counting the letters in their own order, and at this point in the alphabet the count is one ahead of the Greek-derived arithmetic that Cyrillic uses. The distance grows as the order continues.
In the angular hand of the Croatian tradition, as in the rounded hand of the earliest codices, the letter is one of the signs a beginner learns early, since it is common and appears in every kind of text, from the gospel books that carry the earliest surviving Glagolitic writing to the legal and notarial documents produced on the Adriatic coast centuries later.