Here is a link to a website with more information and other links.
I intend to vote FOR the Amendment, but the language you quote is for the ballot only. The actual amendment contains some additional wording. Here is the full text, as I understand it:
“Marriage between one man and one woman is the only domestic legal union that shall be valid or recognized in this State. This section does not prohibit a private party from entering into contracts with another private party; nor does this section prohibit courts from adjudicating the rights of private parties pursuant to such contracts.”
As I said, I will vote FOR the Amendment, primarily for the simple reason that “marriage” already has a definition, and that the state should not be in the business of redefining words.