Multi Value Parameter is used to dynamically filter the report data based on more than one value. This section describes the steps required to create a multi value report parameter in Bold Report Designer.
Refer Create Parameter section for better understanding with the following steps.

Select Allow multiple values, to create a multi-value parameter.
A multi-value parameter cannot include
nullvalues.

Click on Assign Value >> to open parameter assign dialog.

Select Query Value option under Available Value tab.

Select the dataset and fields in the drop-down list and Click OK.

Save the parameter.
Using the ProductID parameter, we can filter the ProductID field values at runtime like below.

Properties icon in the configuration panel, to open table properties.
Table properties, click on Set Filters... button.
Refer Set filters section to create new filter expression.In operator and assign the ProductID parameter in the Value field. Save the filter.

Preview button in the report header. Select the required values in drop-down list.

View Report button.

Download the above report design from link.