data   noun (used as a plural noun in technical English, when the singular is datum)
1 [Uncountable, plural.] facts or information, especially when examined and used to find out things or to make decisions: This data was collected from 69 countries. the analysis / interpretation of the data raw data (= that has not been analysed) demographical / historical / personal data (technical) These data show that most cancers are detected as a result of clinical follow-up.
2 [Uncountable] information that is stored by a computer: data retrieval (= ways of storing or finding information on a computer)

(Advanced Oxford Dictionary)

a) When in a dictionary is said (like in this case) data [Uncountable, plural.], is the word  data Uncountable and Plural at the same time? Or is the word data  sometimes Uncountable and others Plural?
b) If data  is plural, why is the verb in singular and not in plural in this sentence?
1 [Uncountable, plural.]This data was collected from 69 countries.

Thanks.