Learn Finnish: Tällainen tulivuori on liian kuuma. - This kind of volcano is too hot.

Tämä tulivuori means exactly "this volcano" (pointing to one specific volcano). Tällainen tulivuori means "this kind of volcano" or "a volcano like this." You use tällainen when you are describing the type, style, or qualities of the thing right in front of you.

Does tällainen have to match the noun it describes?

Yes! Just like a normal adjective, tällainen must agree with its noun in both case and number. Since tulivuori is in the basic nominative singular form here, tällainen is as well. If the sentence was plural ("these kinds of volcanoes"), it would change to Tällaiset tulivuoret.

I know liikaa means "too much". Why do we use liian here instead?

You use liian directly before an adjective or an adverb to mean "too" (like "too hot" or "too fast"). You use liikaa when you want to say "too much" of a noun or a verb (for example, Hän puhuu liikaa, meaning "He talks too much"). Because kuuma is an adjective, we must use liian.

How does the word tulivuori break down?

It's a very logical compound word! It combines tuli (fire) and vuori (mountain). A "fire mountain" is a volcano.