Product batch

How enter batch number for medicines . And experience date of item

The answer depends on where you are trying to record or show the batch numbers and expiry dates:

If you want to put them into sales invoices, you can use line-item custom fields. See the Guide: Add custom fields for individual line items | Manager.

If you want to be able to track this information in inventory, Manager does not have the ability to track subsets of an inventory item. So you will need to create new inventory items for all batches. You will also need to add custom fields to the inventory items themselves. See this Guide: Use custom fields | Manager.