但

Why does 但 look like this?

The character ⺅ (a person) is on the left, and 旦 (dawn/sunrise) is on the right. Originally, it meant 'bright' or 'only,' but now it's most commonly used as a 'hinge' word to mean 'but'—think of it as a person standing at the break of day, ready to change the direction of a sentence!