On Friday all the town's 18 year olds will be given their printed copy of the Spanish constitution at midday in the town hall.
Then at 1pm there will be a parade from there to the Malecon del Soto by Colla de Dolçainers i Tabaleters Rudimentaria i Pandora d'Onil - traditional Valencian pipes & drums - which will be followed by a show by Muixeranga d'Alacant - Valencian human towers.

Is it a holiday then i.e shops and banks closed?

Yes, both Friday (6th=constitution day) & Sunday (8th=immaculate conception) are bank holidays, so banks & shops closed.

Brilliant Martin thanks for this information! Where will the human tower show be?

On the Malecon del Soto - the park by the water wheel.