Is it correct to use a uuid as a sales order transaction? for example, in an ecommerce website when someones orders any product or products is it ok to use the uuid as a unique identifier for the order transaction?
Yes. It is universally unique, so you can use it as a unique ID for a transaction, or whatever you want to be able to identify maybe cross systems and for storage etc.
You can consider alternatives also - sometimes perhaps also just a sequence number works, if they all come from one place and in order, and it's useful to know the order. With UUIDs you don't have it, unless store the sequence somewhere of course.