Meaning: This sentence describes how the warmth and comfort of friendship surrounds and fills the souls of friends.
Choice of Words: "Friendship's" is the possessive form of the noun "friendship", indicating that the warmth belongs to friendship. "Warmth" is a noun that refers to a feeling of heat or comfort. "Enveloped" is a verb that means to surround or cover something completely. "Their" is a possessive pronoun that refers to the souls of the people mentioned in the sentence. "Souls" is a noun that refers to the immaterial part of a person that is believed to survive death.