Redirects come in a couple of different ways, with the most common being a 301 & a 302 redirect. A 301 redirect is a permanent redirect, essentially telling Google that a particular URL is now indefinitely redirecting to a different one. A 302 redirect tells Google that you’re temporarily redirecting a page, but it’ll come back in the future.
A 301 redirect would, for example, be implemented if you change platforms e.g. from Shopify to BigCommerce, which would result in the URL structure being different, so you’d need to implement a 301 redirect. This, obviously, is hugely important for SEO to maintain value to a page rather than it becoming “dead”, but also for user experience.
A 302 redirect would be implemented typically in an example of a seasonal page e.g. Christmas-flowers, that you just don’t want live year-round for whatever reason, so you temporarily redirect it to a /Christmas page that does live all year round, then remove that temporary redirect when you’re ready to expand the pages.