Not much as an actress
I'll never understand why she calls herself an "actress who sings." She's not that good an actress. A true actress cares most about the role, not simply being the "star" of a piece. A true actress can shine even in smaller roles.
Streisand almost always has to either have a lead, with the exception of those stupid comedies with De Niro. A true actress would do television if the part is exceptional. Her ego has prevented her from ever exploring anything truly interesting in terms of film and performance.