"My mother can sing."

Translation: मेरी माँ गा सकती हैं।

[Catparrot]

Why is there a "hey" at the end here, but not with:
"She can not play."
Translation:वह खेल नहीं सकती।

[vinay92]

In present tense sentences that contain 'नहीं', है ( है/हैं/हो/हूँ) is optional. I am not entirely sure why that is but I've heard that it is probably because नहीं was derived from some variation of ना+है so tacking on another है is redundant.

[Mark701895]

Why is this hain, not hai? Its only one person?

[Zerenei]

Yes but the plural form is used when referring to one person when you want to show respect. So with elders, teachers, parents, etc, you use the plural form.

[Mark701895]

I see. I did wonder if that was the case, but i thought that only applied to males - as the feminine form of words doesn't change for plurals. I assume for hai/hain it applies to both masculine and feminine. Thanks.