Translation:Isn't it early?
It literally is like asking "It's not fast?". Let's say you're afraid of quick trains and you board a train and then ask the person next to you 「はやくないですか」meaning "Is the train not fast?"
The nuance meaning of the English sentence "Is it not fast?" as in "Hey this is fast isn't it?" would be 「はやいですね」
So don't confuse this
"Fast" and "early" have the same meaning here. Consider that if a bus is running 5 minutes fast, that necessarily means that it will be 5 minutes early. はやく and おそく are used similarly.
This can be seen with other words as well, like 高い (たかい) which can mean tall, high, or expensive (a "high" price)
Its tricky because early and fast are homonyms. This is where kanji come in handy. Also, Japanese is super flexible and adding -ない (negative ending) can add character/context like this:
Wouldn't you want that? (Would you not want that?) あれが欲(ほ)しくないです(か)。
Its a little more interesting than just saying:
Would you want that? あれが欲しいです(か)。
Remember kids, context and tone are important!
はやい has two different kanji for the two different meanings. 早い is early 速い is fast In this instance, early is used and we can assume that someone has came to a meeting 10 minutes early and you have just said "arent you early". If we were to be talking about the new train you're riding that is 40mph faster than the old one, 速くないですか would mean "isnt this fast".
actually you would have to add ね instead of か after です for the "isn't it" ending か - makes it a question like: 早くですか- is it early? ね - makes it a statement where you ask someone if he agrees with you 速くですね- its fast, isnt it? also ない after an i adjective (for ex. 早く) makes it negative so what u said before: 早くないですか means " is it not early?"