What does it mean in the Declaration of independence when it says "governments are instituted among men to secure these rights?"

This refers to the rebounding aspect of social contract -- on the government's behalf of course -- in which the citizens have the power to overthrow or replace a government if it misuses its powers, breaking the social contract.

This quote in particular states that it is the government's duty to protect the rights of the people -- rather than taking advantage of the people.

there are no options provided but you can choose among the following gender-neutral pronouns: zir, hir, eir, vis, tem, eir.

in the normal course of maintaining a pronoun-antecedent agreement, we could have used the words his or her but since we are also required to use gender-neutral language, we need to replace it with its equivalent gender-neutral pronoun.

it's