Translation:Is it one o'clock?
一時（いちじ） means "one o'clock", and can be thought of as "the first hour". It follows the convention for telling the time in Japanese, X時(ji) = X o'clock.
The other pronunciations, I believe, are typically written in hiragana to avoid confusion. ひととき or ひと時 and いっとき mean "a short time" or "temporarily", and can be thought of as "one time".
Actually, in Japanese, you only need to add か to make it a question. The question mark isn't strictly necessary, but I like to think of it as indicating a questioning tone of voice, when you're using text-based communication.
一時です。 = "It is one o'clock"
一時ですか。 = "Is it one o'clock?"
一時ですか？ = "Is it one o'clock?"