、。
Second, the literacy rate in Europe at the time was low.
Literal
Second [into-に], at-that-time [genitive-の] Europe [genitive-の] literacy-rate [subject-が] was-low [thing-こと] is.
A list-item sentence, the kind of structured prose that opens with 第一に, 第二に, 第三に when enumerating reasons or points. 第X に ('Xth,' 'in the Xth place') is the standard ordinal enumerator for lists in essays and presentations. The frame ~ことだ at the end nominalizes the entire observation into 'the fact that X' and uses だ to deliver it as an item in the list — 'the second point is the fact that...'. 識字率 ('literacy rate') is a Sino-Japanese compound — 識 (knowledge) + 字 (characters) + 率 (rate).