Adwords is Google's sponsored ad tool. Since it's often very hard to be listed high on Google, they started showing sponsored ads along with regular results. Here is a screen shot of a normal search for "office coffee delivery san francisco":
The top yellow section and the section on the right are sponsored ads, which means businesses have paid to have their ads listed for this particular query. Here is a screen shot of the same screen but with these 2 sections highlighted:
Sponsored ads are listed for free and the business is only charged when someone clicks on the ad.
Before you sign up to have your ad listed for particular queries, some background work should be done. You should:
Once you've determined what keywords you need, sign up for Google Adwords (if you use Little Truck for this service, we will provide you with a $50 credit to start you off).
Once you've signed up, you will need an Ad for your listing (Little Truck has copy writers who can help you with this). You may have multiple ads which will run concurrently.
Just because you've created an ad, doesn't mean you're done. You should look at your ads every month and adjust them as needed, removing ones that aren't doing well and adding new ones (Little Truck can help you by running monthly reports and offering keyword recommendations).
In Google Adwords, if you do nothing, your credit card will be billed once your initial credit (of either $5 if you do it on your own or $50 if you do it with Little Truck) has been used up. You will set a daily or monthly limit so you don't end up being surprised by a giant bill.
The ad listed in the examples is one of our clients. We have a proven track record of high listings at reasonable prices.