Learn German: Dieses Spa bietet viel Ruhe! - This spa offers a lot of peace and quiet!

Spa is a loanword from English, and in German, it takes the neuter gender (das Spa). Because it is neuter, the demonstrative pronoun for 'this' needs the neuter ending -es, making it dieses.

Why do we use viel here instead of viele?

Ruhe (peace and quiet) is an uncountable noun. Just like in English where you say 'much peace' instead of 'many peaces', in German you use the uninflected viel for uncountable nouns. You would only use viele for countable nouns, like viele Spas (many spas).

I always mix up bieten and bitten. Which one is this?

It is a very common mix-up! Bieten (used here as bietet) means to offer or provide. It has a long 'ie' sound. Bitten means to ask for or request, and has a short 'i' sound. Since a spa provides a service, it offers (bietet) peace and quiet.

How would I use this lesson's grammar point (nicht nur ... sondern auch) with this sentence?

To say the spa offers not only peace but also something else, you frame the offered things with the conjunction. For example: Dieses Spa bietet nicht nur viel Ruhe, sondern auch tolle Massagen! (This spa offers not only a lot of peace and quiet, but also great massages!).