Meaning
A six-armed snowflake with delicate branches, usually pale blue or white. It stands for snow itself as well as the crisp feeling of freezing air.
It means cold, winter, frost and anything icy, from weather to air conditioning: “Office AC is set to ❄️ again, bring a jacket.” In English slang, calling someone a snowflake suggests they are overly sensitive, so context matters. It is also a favourite festive decoration.