When you have an object with data that you want to update your model with, like when you have submitted a form, it's very cumbersome to have to assign each value to the model.
Example
/// Instead of
const data = { name: 'Chair 1', price: 42.00 }
const product = Product.find(id)
product.name = data.name
product.price = data.price
await product.save()
// Do
const data = { name: 'Chair 1', price: 42.00 }
const product = Product.find(id)
await product.update(data)