Ember where is this.get() looking?

I've been looking through all of the code of ember-power-calendar and I am trying to change the selected value to have another item in its object.

On this line, it's calling for selected: this.get('selected'), but I can't seem to find where it's getting 'selected' from. Is it looking outside of its own file? The imports aren't very descriptive, but I have a feeling it's in one of them:

import Component from '@ember/component';
import { computed } from '@ember/object';
import { guidFor } from '@ember/object/internals';
import { inject } from '@ember/service';
import moment from 'moment';
import { task } from 'ember-concurrency';
import layout from '../templates/components/power-calendar';

No where else in the file has a method called selected, so I'm wondering where it's getting this value from?