No one would need "a thread" in English. You might "have a thread," but that means you have a thread hanging from your clothing. If you are sewing, you need some thread, or a piece of thread. "A thread" would only work for something like the threads in email or online comments, and you'd rarely say someone needs a generic one of those.

Could also be interpreted, " He needs a thread." ?

it could.

Why not "she needs thread" probably the most proper English

The better English translation would be "He/she needs thread."

Could it be "she need a yard", right?

what is wrong I can write one of them the male version or the female one why are they forcing me to write both at once

The sentence can be translated as "he needs thtead" or "he needs a thtead." Both should be accepted