Questions & Answers about Tv on vanha, mutta sivusto on uusi.
What is the difference between sivu and sivusto?
Sivu means "a page" (like a page in a book or a single web page). The suffix -sto or -stö is used in Finnish to indicate a collection or group of things. Therefore, sivusto literally means a collection of pages, which makes it the standard word for a "website". You have likely seen this same suffix in words like kirjasto (library, from kirja) or laivasto (fleet/navy, from laiva).
How is the abbreviation Tv treated in spoken and written Finnish?
Even though it is an abbreviation, it functions as a completely regular noun and is pronounced as teevee. In modern written Finnish, well-established acronyms are often written in lowercase (tv) when in the middle of a sentence, rather than in all caps. Here it is written as Tv simply because it is the first word of the sentence.
If I wanted to say "the site is a new one", how would I add the word "one"?
You wouldn't add anything! In Finnish, adjectives like vanha (old) and uusi (new) easily stand on their own. While English requires the dummy pronoun "one" to say "a new one", Finnish leaves it out completely. You use the exact same phrasing to mean both "the site is new" and "the site is a new one": Sivusto on uusi.