Custom Metadata Types and Process Builder

Reference custom metadata type records from a Process Builder formula to automate your business processes, reusing functionality that you define. To change a value, you can update it in the custom metadata type instead of in your process and any hard-coded formulas that your process uses.

EXAMPLE: Let’s say that you want to send an email or trigger some other action when the amount in the Account object’s Annual Revenue field is greater than $100,000.

1. Create a custom metadata type.
2. Create a custom field for your type named Minimum Revenue.
3. Create a record for your type, and name it FY20.
4. Reference the custom metadata record in Process Builder.$CustomMetadata.CustomMetadataTypeAPIName.RecordAPIName.FieldAPINameUse the correct suffixes. For the custom metadata type, use __mdt. For fields, use __c. Records require no suffix. Your formula might look like this one.[Account].AnnualRevenue > $CustomMetadata.Annual_Revenue__mdt.Annual_Revenue.Minimum_Revenue__cIf the minimum revenue amount changes, edit the custom metadata record rather than your process.

For More Details : https://help.salesforce.com/articleView?id=custommetadatatypes_process_builder.htm&type=5