Although many bands and discos will provide their sound and lighting, additional may be required.
This may be a PA system for daytime conferences, talks and presentations; and also for speeches during the evening events. (Yes, you can use a microphone for the disco or band, but they aren’t really set for plain vocal (having too much bass and reverb.)
Additional light may be required to add atmosphere and ambience, and to complement the decor. This may be something like coloured up-lighters.