As a suffix, 性 turns adjectives into abstract nouns, similar to English '-ness'/'-ity': 可能性 (possibility), 重要性 (importance), 创造性 (creativity), 必要性 (necessity).
usage
性 alone can mean 'sex/sexuality' in modern Chinese, but in compounds it's usually neutral: 性别 (gender), 性格 (personality), 个性 (individuality).
