You can work with issues the same way like you are used to within Jira. Issues can be configured depending on issue type and will display the expected field and have the behavior determined by its workflow.
Find Issues
There are several way in which you can find issues.
Home Screen - Quick Search
If you know part of the issue key or a keyword you can simply go to your home screen and enter it in the top search bar (Android: you will need to press the magnifying glass icon first). The Mobility app will display a matching list of issues, projects, dashboard, and filters. If your Jira instance is large you may want to be more specific to create the result needed.
Home Screen - Search Shortcut
On the Home screen, press the Search shortcut.
Basic Search
You can use the Basic search mode to find issues. You can provide search criteria by selecting one or multiple values for each field by pressing on the field button underneath the search bar text field. To view more fields swipe the field list to the left. In addition you can enter text into the search bar text field. All values are used in AND search operation.
Advanced Search
To find issues using advanced search (JQL), press the Advanced text link to the right of the search bar text field. You can start typing JQL. The app has a type-a-head/autocomplete feature that allows you to select an option without fully typing it. After typing a few characters you will see options appearing on the bottom of the search bar text field. Select one of the options and the JQL portion will be populated in the search bar.
Home Screen - Search with QR Code
If your organization uses QR codes and real-world objects are tagged with codes that match issues or issue fields in Jira, you can search for issues via QR codes. You will need to configure a Scan Shortcut on your Home screen. View the documentation here.