Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means display, so if you're doing the action of displaying something, you're going to put up something, or, sometimes more specifically, to put up a sign.

You have to put up a sign for your newest invention, the car car (かか). It is a car made so that other cars can drive the car. Nobody wants to buy it, which is why you have to put up a sign.