Singapore has two different codes, each representing a different meaning:
SIN:
SIN is the IATA three-letter code for Singapore Changi International Airport. IATA codes are commonly used for communication between airlines and airports in flight identification and reservation systems. Changi Airport is the main international airport of Singapore and one of the busiest airports in the world.
SGP:
SGP is the ISO 3166-1 alpha-3 country code for Singapore. ISO 3166-1 is an international standard that defines a set of codes for every country and region in the world. SGP is used in various international contexts, such as sports events (like the Olympics), international trade documents, internet domain names, geostatistics, etc.
To summarize:
SIN is mainly used in the aviation industry, specifically referring to Changi International Airport.
SGP is used to represent the country of Singapore itself and is used in various international settings.
PS：The original dataset provided on Kaggle also has this problem, but the data provider has not corrected it either.