Figures are number of people (#). Geo coverage is 210 individual countries and 48 country-aggregates; not all concept-geo pairs exist. Series start as early as 1960 and are currently projected out to 2050.
Series reside in the historical catalog (Cross-Country Datasets » World Bank » Population Projections » by age) and include, for example:
Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.
References