The value coming from Salesforce will come with the Data Type. Default Data Formatter will format Salesforce data throughout the document. If you need to format one field in the document differently with the rest, create a Custom Data Formatter and apply that to the field in the template.
By default, data format will follow the end-user's default locale or from their personal setting in Salesforce. The patterns, symbol for grouping numbers, separating decimals and abbreiviation for months and days are locale's properties.
In general, you don't need to edit locale in data formatter. It's good to know which locale users are using and understand how it influences to data format. In case you want to customize locale. The Locale value should be a combination of an ISO-639 language code and an ISO-3166 country code, joined by a hyphen or an underscore (eg. "en-US" or "en_US").
The below instructions are how to customize the data formatter to partly or fully override locale's format.
Occasionally you want to format data from a specific element differently than the rest of the document. To achieve that, you need to create a Custom Data Formatter and apply it to the Content Format attribute of that element in the template.
Create a Custom Data Formatter
In Settings tab -> Salesforce Data -> Custom Data Formatter
Click + and select the Formatter you want to add
Give the name for the new Custom Formatter
Format the pattern and other properties as you wish, following the same instruction with editing the Default Formatters above.
Apply Custom Data Formatter to element
In the template, select the element you want to have special format
In the Tags on the right pane, select Attributes
In Content Format attribute click ... button to see different formats and select one. If custom data formatter is added manually you need to use the single quotation, for example 'NewCurrencyFormatter'.
Now the dynamic data coming from Salesforce will be format with the Custom Data Formatter