A bowed psaltery (as in, a bowed string instrument) is probably one of the easiest instruments to learn to play. Psaltery is pronounced with a silent p, it sounds like salt-tree, with emphasis on the first syllable.
A modern bowed psaltery is a shallow triangular prism shape, which is grasped in the left hand about halfway up with the base against the torso. There are pins placed regularly on the right-hand side, each with a string that's also tied to a pin on the base of the triangle immediately below. These correspond to the musical notes A, B, C, D, E, F, and G. On the opposite side, at appropriate intervals, are pins and strings for A#, C#, D#, F#, and G#. (The instrument I saw, at a Renaissance festival, had 30 strings, or about two and a half octaves.) A bow is held in the right hand, near one end (so the majority of the bow is to the left). To play a note, the bow is pressed against the appropriate string (just below the pin) and drawn sideways across it. The bow is tipped up to play notes on the right-hand side, and enough of the bow should be to the left that notes on the other side can easily be played by tipping the bow down. The note corresponding to each string is printed beside the appropriate pin, so it is very easy to locate any particular note.
The above description is of a right-handed instrument. Left-handed instruments are also made, which are mirror-images.