[Vuejs]-How can i passing data props to "units" form and v-model?

You only have 1 unit in your units array. Try setting your units like this.

data (props) {
        const form = reactive ({
            invoice_code: props.invoice.invoice_code,
            customer_name: props.invoice.customer_name,
            units: units: props.invoice.units,
        })
        function update () {
            Inertia.put(`/invoice/`+ props.invoice.id, form)
        }
        return { form, update }
    },
    props: {
        invoice: Object,
    },
  }