The number indicates how many persons or things are spoken of. In New Testament Greek, as in Dutch, there are two numbers: one or more. We speak of singular and plural number, or shorter: singular (ev) and plural (mv). When a word form indicates a singular or plural number, the abbreviation of this fact (ev or mv for singular and plural, respectively) is added in parentheses to the translation of the word form, unless this is obvious from the translation, e.g., under word 3970 sapros "rotten, spoiled.
.1 sapros rot (1 ev m)
but under word 3969 sanis "plank; plank object.
.1 sanisin shelves (3)

See further at grammar.