[Vuejs]-How to use object prop in Child component using Vue?

Try v-bind:legend="legend" instead of v-bind="legend"

The legend on the left is the props that the child component declared, the legend on the right is the data/property from the parent.

For example if your children declared:

export default {
  props: {
    givemelegend: Object
  }
}

Then in Parent.Vue, you would want: v-bind:givemelegend="legend"