Hmmm....those are add-on temporary tow lights- they stick to the bumper with magnets.
Clearly, either the tow vehicle connector didn't match the trailer, OR- you won't like this- the lights
on the trailer don't work.
Is he letting you have those lights? If not: if you're planning on bringing this trailer home on Saturday, you might want to invest in a set of those yourself. You can buy them for about thirty bucks, and if it turns out you don't need them you can take them back to Walmart or wherever.