An Iambic paddle is a very common piece of a ham radio shack. It has 2 finger pieces. They are pressed with either the thumb or index finger to generate Morse code.

Nearly every modern radio has a built-in keyer that can generate the code for you.

Which side does shorts/longs?
That depends on what you prefer. Generally, the shorts on the thumb.

What are some good paddles?
Bencher BY Series

Vibroplex

Begali

N3ZN