订 (dìng) means “to agree”. The 订 stroke order has 4 strokes; the animation above shows them one at a time. Its radical is 讠. To practise how to write 订, open writing practice; to hear how to pronounce 订, use the pronunciation trainer.
Words with 订
订 — dìng, to agree; to conclude; to draw up; to subscribe to (a newspaper etc); to order
制订 — zhì dìng, to work out; to formulate
签订 — qiān dìng, to agree to and sign (a treaty etc)