An alias is an additional email address that delivers to an existing mailbox, rather than a separate inbox with its own login. Someone can receive mail at both jane@yourdomain.com and support@yourdomain.com in the same inbox if the second address is set up as an alias of the first.
When an alias is the right tool
Aliases work well for department addresses routed to one person (like info@ or billing@), for someone who needs to receive mail under a previous name during a transition, or for shorthand addresses that should land in an existing mailbox.
When it is not
If more than one person needs to see and respond to the mail, a Group is usually the better fit than an alias, since a Group can have multiple members and its own permissions, while an alias always delivers to exactly one mailbox.
Sending as the alias
Receiving mail on an alias is automatic once it is created, but sending mail that displays the alias as the "from" address requires an additional "Send mail as" configuration inside Gmail’s settings — the alias existing in the Admin Console is not enough on its own for outgoing mail to show it.