Alla giardiniera can be a contorno made of garden vegetables, or a dish (usually pasta) served with diced vegetables.
On its own, giardiniera usually means pickled vegetables (carrots, cauliflower, green beans, red peppers etc) or sott'aceti, served as part of an antipasto or with a sandwich. The Tuscans add it to their version of salsa verde.
Image by Antonio Cavallo, Creative Commons License