The TABLE keyword introduces a table definition (DEFINE) in a query (also known as query table).
The syntax after TABLE defines a query table, which has a data lineage and it is populated in an empty filter context before the query is executed.
The following example shows using a query table in a DAX query.

DEFINE 
    TABLE Colors = DISTINCT ( 'Product'[Color] )
EVALUATE
ADDCOLUMNS (
    Colors,
    "Sales Amount", 
        CALCULATE ( 
            [Sales Amount],
            TREATAS ( { Colors[Color] }, 'Product'[Color] )
        )
)