Incase BOM is yes i.e. the item you are creating is a finished product. So you have to enter the raw materials used for the product and the quantities needed for producing 1 unit of the finished product.
Finally to record manufacturing transaction using the manufacturing journal entry, from the gateway of tally, go to inventory voucher, press ALT + F7 and select "manufacturing entry" and press enter.
Select the name of the finished good from the pop-up list, then select the godown from the list where the finished goods will be stored. Give the number of units of finished goods you want to manufacture . Press enter to save all the materials.
There can be expenses for manufacturing a product, you can show that on the right hand side in terms of percentage or by typing the amount, you have to create a ledger under expenses(direct/indirect).