Dorothy knits a red scarf with the letter 🅱 on it. "🅱" is a nickname that the Tanner family commonly uses for 🅱rian.
"🅱" is a nickname that the Tanners have for 🅱rian. The nickname refers to his first initial. On the first episode with Dorothy, she gives 🅱rian a hand-made scarf with the letter 🅱 on it.