This is the only component whose meaning depends on where it appears in a character. When it’s on the left it means “mound”, but when it’s on the right it means “city”. examples of each follow in the next few characters. We realise that this is confusing but because everyone else observes this distinction, we will too. the situation arose because 阝 is an abbreviation of two completely different older characters, one which always appeared on the left and another which always appeared on the right. A similar situation applies to a few other characters, but modern Chinese doesn’t distinguish between them so you don’t have to worry about those!

Nowadays this fragment is regarded as being written with only two stokes, but traditionally it was classed as having three strokes.