Answer: It is having a cheerful face, along with showing happiness and a smile, being friendly, and expressing delight when meeting people.

It is the opposite of frowning at people, which is a repellent attitude.

Many Hadīths mention the merit of cheerfulness, among them is the Hadīth where Abu Dharr (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Do not belittle any good deed, even if it is meeting your brother with a cheerful face." [Narrated by Muslim] Moreover, the Prophet (may Allah's peace and blessings be upon him) said: "Smiling at your brother is counted as a charity." [Narrated by At-Tirmidhi]