Domain Name redirection - What is the effect? (new domain to old domain sub pages)

[SEO]

Hi, If i buy a new domain name let say example123.com and i redirect it to my exisiting page let say example.com/123. What is the effect? what metadescription will the bot detect? (example.com/123's meta description? or is it just empty?) will example123.com even get indexed in google? let...