How we perform Platform Encryption on standard Account and Contact fields in Salesforce?

Hi Piyush,

For platform encryption, select the fields you want to encrypt. For your information, when a field is encrypted, its value is masked for users who don’t have permission to view encrypted data.
Please follow below steps:
1. Make sure that your organization has an active encryption key. If you’re not sure, check with
your administrator.
2. From Setup, use the Quick Find box to find the Platform Encryption setup page.
3. Click Encrypt Fields.
4. Click Edit.
5. Select the fields you want to encrypt, and save your settings.

Thanks