Salesforce Platform licenses are for the customers who want access to custom apps like Force.com or AppExchange but NOT the standard CRM functionality.
Salesforce Platform users will have access to the main Salesforce Standard Objects and functionalities such as
- Accounts
- Contacts
- Reports
- Dashboards
- Documents
- Custom Tabs
If you are looking for an online course to learn Salesforce, I recommend this Salesforce Training Course by Intellipaat.
Also, watch this video to understand more: