外边 (wàibian) is the most common HSK1 word for 'outside' as a location — the space outdoors or beyond an enclosed area. It is more versatile than 外 (wài), which is usually a prefix or part of compounds (e.g., 外国 'foreign country'), and very similar to 外面 (wàimiàn), though 外边 is slightly more colloquial in everyday speech.