卡 – traditionally means ‘stuck’ is comprised of the characters 上 ‘up’ and 下 ‘down’. It is a pictorial way to illustrate it is neither up or down. It can even be seen as both up and down.
It is pronounced as ‘kar’ in Cantonese and it is often used to pronounce words/names in foreign languages. The most common example is card. It is used to describe an object in a form of card in Cantonese. A piece of card ‘卡片’ is referred to as ‘business card’.
The fact that this character use as a sounding word most of the time, it is difficult for people to appreciate its meaning and form.