I developed a few automated flows and when creating the changeset, there is an option to add profiles. I went through the salesforce documentation, but could not find out the exact use case of adding profiles. Like how would a profile relate to a component that is in the changeset?
If you add profiles to the changeset then all the access rights defined in the profile will be enabled in the destination org. This access rights could be object level access, FLS, recordtype, page layout assignment etc.
If you do not add profiles in the changeset then after deployment you need to provide those access rights explicitly to those profiles.
@I am just extending satanu boral answer for your understanding
You have not changed any permission in profile,then you no need to do any thing
Just explaining the answer considering apex class and visualforce page.
If you created new apex classes,visual force pages. now you are pushing that changes to production.
Suppose you haven't added profiles in change set,then you have to perform that steps in production as a post deployment activity.
If you have pushed apex class ,visualforce page etc along with profile then you no need to perform that operation,you can save the time in Production.