ちょっと時間ある？って英語でなんて言うの？

To have a word with someone = to speak to someone about something. This expression may be used formally or informally and usually there is a specific topic to be discussed. the speaker knows exactly what he wants to say. It is not a casual chat.
All of these expressions should be accompanied by the correct body language and facial expression appropriate for this situation. It depends what the 'word' is about.

"Are you free?" asks a person if they were available to talk or to ask a question.

A minute and a moment are the same thing in this sentence, they mean that you would like to speak to someone for a short period of time.

A sec is a shortened version of second. It does not mean that you only want to chat for one second, it is just a term, similar to the way minute or moment is used above; to denote a short period of time.

When asking someone if they have some time for a question it is important to remain polite. You may make use of any of the examples above.
time to spare-Time on one's hands, not in a hurry.
steal a moment of one's time- A common expression used to ask if someone has some time to spare for a quick chat.
would you mind...?- A polite way to ask if someone has some time.

The three sentences above a great ways to ask someone for a moment of their time, whether to ask a question or express some other statement. The first two sentences would be appropriate in an office or business setting. The last sentence would be appropriate in an everyday conversation with a close friend or family member.