Do I need to file extension for 2019. My husband and I are separated. We had been filling Married/Joint. He said he was filing for a 2019 extension as Married/Seperate. I have no income.

It doesn't sound like you do - if you have no income and your husband is filing his own return under Married Filing Separate status, there's no need for you to file a return for yourself, hence no extension.

An extension just gives you more time to file, but I can't see why you'd be filing anyway.

If you have no income and will not be required to file a return, an extension is not necessary.  If you aren't sure, you can file one anyway (it won't hurt anything).  You can file one quickly, for free, here: TurboTax Easy Extension.