Refers to a person's disposition or skill in social situations; often used when describing personality traits or job requirements.
彼は社交性が高く、誰とでもすぐに仲良くなれる。
He is highly sociable and can quickly become friends with anyone.
This job requires sociability.
愛想 refers to a person's friendly, easy-to-approach manner in everyday interactions, while 社交性 is the more formal term for one's general sociability as a personality trait.
Compound of 社交 (しゃこう, 'social intercourse') and 性 (せい, 'nature, quality'). The exact historical derivation is uncertain, but the word follows a common pattern for abstract nouns in modern Japanese.