All amplifiers will have an input where a cable or even wireless transmitter can be plugged in. You want to make sure the cable is specifically an instrument cable, preferably 10' or longer. Sound in an electric ukulele won't make much noise unless it's plugged in, similar to an electric guitar. However, your ukulele will need to have a pickup installed so that the sound can travel. A pickup is similar to how sound travels, and our brain picks up the frequency so that we can hear it. An amp working with a ukulele is the same thing. The ukulele makes the signal, and the cable connected to the amp converts the vibrations from the ukulele into an electric signal. Some amps come with cables, some don't. It's important to keep that in mind.