"Surroundings" is a plural noun. Some nouns, like "surroundings", cannot be used in the singular.
"Surroundings" is a plural noun. Some nouns only have a plural form and cannot be used in the singular. They are known as pluralia tantum (Latin for "plural only").
The surroundings are quiet and pleasant.
The surrounding is quiet and pleasant.
The word "surrounding" (without "s") is an adjective, not a noun.
We used to explore the surrounding countryside in summer.
Note that pluralia tantum require a pronoun and a verb in the plural. Therefore, you can say "surroundings are", not "surroundings is".
Its surroundings are idyllic.
Its surroundings is idyllic.