Not much as an actress

Her singing is what gave her an acting career.

https://www.quora.com/Why-doesnt-Barbra-Streisand-make-movies-anymore/answer/Jon-Mixon-1

Her last two film outings were legendarily trashed by critics - Little Fockers and The Guilt Trip were Streisand's last feature films, and both were spectacularly terrible. Critics were particularly harsh about Streisand's performances and she may not want that to occur again.

She'd have to sing - Barbra Streisand was never a beauty queen, nor a great actor. Given that she's now in her 70s, the only thing that would make her appealing to cast would be her singing voice and she hasn't been willing to sing in films for several decades.

She never made many films, even at the height of her career - Streisand has made roughly 25 films in her 60 year performing career. That includes the dozen or so where she was the lead. Her publicity machine has done an exceptional job of making Streisand appear to have been a busy working actor, when it reality she hasn't done much film work at when compared to her peers.

Streisand has problems - During the early 1980s, Streisand's personal behavior became odd and she gave several interviews where it was clear that she was suffering from sort of anxiety disorder. She never seems to have dealt with that successfully and that may have convinced productions not to cast her simply to avoid the difficulties.

She hasn't been a major box office draw in decades - If the 1981 film, The Main Event with her and Ryan O'Neal had been a hit, it's likely that Streisand would now be a “grand dame” of Hollywood cinema. However it wasn't and her further film offerings did moderately well with audiences, but weren't hits. A 70+ year old performer who can't bring in filmgoers isn't appealing in Hollywood and never has been.

Barbra Streisand had an opportunity to become a bigger star in the 1980s and that time has passed. For the reasons above and host of others, she's no longer considered for productions.

You know the line from MY FAVORITE YEAR?

"I'm not an actor, I'm a movie star!!"

Well, Babs is a movie star! Real actors change with every role, movie stars carry the same persona from role to role, because their fans want to see the established persona in new settings and new outfits.

She can't act and she is full of evil hatred but at least she had an "effect" named after her. That's impressive IMO.