In Odoo, lots and serial numbers have similarities in their functional system but are different in their behavior. They are both managed within the Inventory, Purchases and Sales app.
Lots correspond to a certain number of products you received and store altogether in one single pack.
Serial numbers are identification numbers given to one product, in particular, to allow tracking the history of the item from reception to delivery and after-sales.
First, you need to activate the tracking. To do so, go to Inventory ‣ Configuration ‣ Settings and tick Lots & Serial Numbers. Then, click on save.
Now, you have to configure which products you want to track by Lots/serial numbers.
Go to Products‣ Products and open the product of your choice. There, click on Edit and select Tracking by Lots or by Unique Serial Numbers in the inventory tab.