The kanji and the radical are the same, so remembering the meaning of this kanji is as simple as making sure you know the radical for writing first! If you know the radical, you know this kanji means writing as well.
This kanji has more than one important reading you need to learn, sorry! But don't worry, here's a mnemonic to help you:
When you're writing you need things to fuel you. That's why you always eat buns (ぶん) while you write. Bread bun, hot crossed buns, whatever as long as they're buns, they're great writing fuel.
When buns aren't enough, you call in the monster (もん) that lives under your bed. It pretends to chase you, motivating your writing even further, because if you don't write fast, you'll die by monster bites.