Exact match keywords means that you place your keywords in brackets  and only people searching for that exact term will see your ad. So, if your keyword is “blue cars” then your ad will show up only when people type in “blue cars” exactly and not “buy blue cars” or “used blue cars” or even “blue car”.
Phrase matches allow you to access a wider target market. These keywords are contained in quotations “” so, continuing with our same example, “blue cars” will show your ad whenever people type in searches such as “used blue cars”, “big blue car”, “sell blue cars”. On the other hand, your ad will not show up for a search such as “blue used cars”.
Broad match terms are those without delimiters so you would simply type your term in as blue cars. If you don’t add negative keywords your ad will show up for everything from blue cars photos to a blue sedan type car that looks cool.