To set up your SharePoint List alerts, open your Lists app and go to the "Alert me" menu by clicking the three dots on the ribbon.
Alert settings in Sharepoint List
In the pop-up, you will see all the alert settings. You can receive alerts by E-mail or by SMS. You can also choose different conditions according to which you receive alerts.
All the alert settings in SharePoint List
Notifications in SharePoint List
Follow the link to Microsoft support if you want to learn more about what each item in the settings means.