Classic encryption lets you protect a special type of custom text field, which you create for that purpose. With Shield Platform Encryption you can encrypt a variety of widely-used standard fields, long with some custom fields and many kinds of files. Shield Platform Encryption also supports person accounts, cases, search, approval processes, and other key Salesforce features.
For implementation, check the below link
To know more, check the below link
Manage Encryption Keys – Permission to manage Shield Platform Encryption.
View Encrypted Data – Permission to view the encrypted fields.