Many members find they need to send emails to people and companies they do not know.
If you just send an ordinary email, or fill in an online form with your usual email address, the person at the other end gets your real, working email address.
If they are trustworthy, that is probably not an issue. But, even then, in this era of data theft and hacking, your email address could end up anywhere.
And if they are not trustworthy, you could be deluged in spam and other unwanted email.
In order to avoid that, several companies have set up ways of hiding your real email address but still being able to communicate with people. Effectively, they add a new email address which the person at the other end sees, but mail gets sent on to your usual email account. Most of them refer to "relay" because that is what they do - they relay email between this new address and your real email - in both directions.
Typically, you'd set up a new email address for each new contact/company.
If you get unwanted email, you can turn off that new address.
I have found a pretty good article about this - unfortunately from December 2021 so a bit out of date. Nonetheless it should help you to get started.
If you don't understand, don't worry. Mostly, the worst that will happen is an excess of spam. As for so many things, it is probably much easier to set up on a laptop or desktop than a phone, if that is an option for you.
How to hide your email from data collectors
Preventing spam and tracking
theverge.com/22792380/email...
If you are a paying user of Apple's iCloud (even the lowest cost band), you have access to Hide My Email and I would unhesitatingly recommend that if you are an Apple user. It has the classic "it just works" that Apple claim - in this case, that claim is pretty accurate. Especially if you use an Apple iPhone or iPad or multiple Apple devices.
If you need to search for a company offering email relay, be careful. Inevitably there are some very dodgy sites seeming to offer these mail relay facilities. You really need a company that will be around for as long as you want to use the email relay.