Hello and welcome to the website. You may want to take a look at our help center to get a sense of how Stack Exchange is supposed to work. It is especially important to read the provisions on asking questions, since if they are not obeyed the question will normally be put on hold and eventually closed until it is brought into compliance, but that seems to be irrelevant to the subject at hand.
Reputation is a score of points that is associated with your account. It is somewhat like money, in that it serves as an incentive, and represents an assessment of the value of the contribution you have made to the to the website, as determined by votes. You get +10 for each vote for one of your answers, +5 for each vote on one of your questions, and lose -2 for each vote against any answer or a question. Under certain conditions, you can also get +2 for suggested edits that get approved for qualified users. Our members can also pay bounties of various amounts in a bid to attract good answers to a question, or award an especially good existing answer. You do not earn or lose reputation points for questions and answers made at the meta website.
Reputation points are used as a sort of proof of trustworthiness, not only because they suggest that you have a minimum extent of knowledge as determined by the sum total earned through all of your contributions, but are also used to control access to privileges. That is done on the basis that people who have reached a requisite amount should know how the website operates well enough to use them properly and can be expected to do so or face the consequences, without simply being able to create a new account to bypass a suspension or ban to abuse them. Here is complete list of privileges, with the amount of reputation necessary to accesss them. You earn the ability to comment once you earn 50 reputation points. If you contribute a few good answers to our website, you should be able to reach that amount of points relatively quickly.
When you earn the privilege please keep in mind that on Stack Exchange, comments are supposed to serve a specific purpose. They are not supposed to be used as substitutes for answers, permanently archive information or be used to participate in extended discussions. They are primarily reserved for a sparse amount of constructive criticism which leads to the improvement of a post, with a few secondary purposes which you can read more about on the help center page for the commenting privilege.