Google Ads allows you to apply different settings to each keyword you bid on. These are called matching options and determine how well the keyword should match the search term in order to trigger your ad. There are four main criteria for this: broad match, phrase match, exact match and negative keywords.
In order to apply one of the mentioned options, you need to add a keyword to the ad group and respect certain principles. If you want it to be broad matched, just type it, and if you need a phrase match, put it in double quotes. For an exact match, the keyword must be enclosed in square brackets, while negative keywords are defined by adding a simple dash representing the minus sign.
You will certainly use some of these criteria in your campaigns, so I recommend that you pay special attention to them.