When you download data from for example CompuStat or Worldscope you have to know the scale of the item: is it stated in millions or thousands?
In CompuStat check the CompuStat Online Manual (available in WRDS > CompuStat > Manuals and Overviews). Search for the item – on top of the definition you will see the units:
Datastream – Economics
In the Data Category Economics you can request the unit in a Static Request. The datatypes are Unit of Quotation and Unit Qualifier.
For other categories in Datastream the unit is often hidden in the definition of the datatype. For example Number of Shares (Mnemonic: NOSH) is expressed in thousands.