The Russian word for "ready" is "готов". It is a short-form adjective. The ending changes depending on whether you are talking about a group, just one male person, or just one female person. It works like this:
|He is ready||Он гото́в|
|She is ready||Она́ гото́ва|
|They are ready||Они́ гото́вы|
So if you were asking a group, you would use the plural form and say "Вы готовы?".
If you are speaking to someone with whom you might use a title such as "Mr.", "Mrs.", or "Professor", you show respect by addressing the person as you would a group. So you would still say "Вы готовы?"
If you are addressing a family member, a close friend, or a child, then you must pick the form of "готов" which matches the person's sex.
When you say you are ready, you pick the form of the word "готов" which matches your own sex.
If you are answering for a group, you will use the plural form of "готов" to say "We are ready."