“Keyword match type” is a setting in Google Ads that lets you further refine when your ad will show up on Google. There are five options:
The “broad match” setting shows your ad for searches that contain your keywords in any order, and for related terms. This option shows your ad in the broadest variety of searches, and is the default setting for all campaigns.
Broad Match Modifier:
This setting allows you to specify that certain words in your broad-match keyword must show up in a user’s search to trigger your ad. So, if your keyword is “high fiber wool yarn” and you wanted to make sure “wool” and “yarn” were always present in a search, you could ensure that by adding a plus sign (+) before those words. So, your broad match modifier keyword would be: high fiber +wool +yarn.
This option shows your ad for searches that contain your exact keyword, or for searches that contain your exact keyword plus words before or after it. (I.e. if your keyword is “wool yarn” you might also show up for “fine wool yarn” or “wool yarn for sale near me.”) To choose this option, you should add quotation marks around any keywords, i.e. “wool yarn”.
When you choose exact match, your ad will only show if someone searches for the exact word or phrase you choose. For this option, put brackets around your keyword, i.e.: [wool yarn].
This match option allows you to exclude undesirable words or phrases from triggering your ad, weeding out irrelevant traffic. For instance, if you only sell high-end yarn, you might want to exclude words like “bargain” or “cheap.” You can do so by putting a minus sign in front of the words you don't want to show up for, i.e.: -cheap, -bargain.
Video Resource: https://www.youtube.com/watch?v=m4SaXPVidWk