What is the meaning of Da-?

deca- (“×10”); Alternative form of dk- (“deka-”)

prefix form of da, meaning there-

third person plural nominative proclitic

her (object pronoun)

them

question marker

third-person singular possessive prefix, its

indicates definiteness

joins stative verbs attributively

third-person plural clitic, they

third-person singular clitic, he, she

Thematic prefix, referring to death.

Distributive plural marker, indicating that three or more subjects, objects or events are involved individually in the action denoted by the verb. In addition to verbs, it may also pluralize postpositions.

Forms the distributive plural of nouns and pronouns equivalent to "many"

Source: wiktionary.org