This is a white small medium square, its reduced version is
▫️ white small square, the enlarged version is
◻️ white medium square and
⬜️ white large Square. On the Internet, people use it as a white color card, or as a decorative symbol for text content. When it appears with
◾️ black squares, we think of mosaics. Related emojis：
⚫️ black circles,
⚪️ white circles.