Learn Romanian: Acest unt este foarte scump. - This butter is very expensive.

Acest means "this" for masculine and neuter nouns in the singular. The word for butter, unt, is a neuter noun, so it takes the masculine form acest. If it were a feminine noun, like apă (water), you would use această.

Does the word for expensive, scump, change to match the noun?

Yes, adjectives in Romanian must match the gender and number of the noun they describe. Because unt acts like a masculine noun in the singular, we use the masculine singular form scump. For a feminine noun, it would change to scumpă.

Can I change the word order and say unt acest instead of acest unt?

Not exactly. When "this" comes before the noun, you use acest followed by the simple noun (acest unt). If you want to put "this" after the noun, the noun needs a definite article ("the"), and the word for "this" changes slightly to acesta. So you could say untul acesta, which also means "this butter".

Will foarte change if I'm talking about a feminine or plural noun?

No, foarte (very) is an adverb, which means its form never changes. You will always use foarte exactly like this, regardless of the noun's gender or whether it is singular or plural.