Meaning
A police officer in a peaked cap with a badge on the front, representing police, law enforcement and public order. This is the gender-neutral version; man and woman versions also exist, and all three come in several skin tones.
Besides real news about police, it is often used for playful rule enforcement among friends, such as the grammar police, the diet police or the spoiler police. A siren ๐จ is the usual partner: โSpoiler police here, delete that comment right now ๐ฎ๐จโ