Time is often displayed on a watch dial in two ways, with rotating hands or with digits/numbers. For watches with rotating hands, they often rotate just in-front of the dial and the dial would have markings around the edges so you can read the time in 12-hour format.
A watch will often have three hands for hours, minutes and seconds. You may also just get two hands (often hours and minutes), just one hand for hours or maybe seconds for example might be displayed on a subdial. The hands tend to be made of metal, where similar to the dial you might stamp them out of a sheet of metal, and may be designed to match the dial or a particular look.
You might get all three in a particular shape with varying sizes, with the hour hand generally shorter, or the hour and minute hands might be a certain shape with the seconds hand being fairly plain and thin. The hands might be one colour, of the material used or a colour painted over it, or for hands that are fairly wide another colour/material might be added along the edges.
The hands might be a flat two-dimensional shape, where the sides are plain and follow the same shape as the top, or a more three-dimensional shape, faceted for example where it might have a triangular shape from the side with the middle part taller and the sides thinner/nearer the dial.
There are hundreds of potential shapes that might be used, but certain general types are used quite commonly. We go through these types below.
Arrow hands
Arrow hands are shaped like an arrow, where it often points outwards to the dial ring. The triangular part at the top of the arrow is often flat, sometimes slightly curved on the side nearer the middle of the dial. The main part below the triangle might be flat or faceted and is often wider nearer the middle of the dial than the area just below the triangle.
Baton hands
Baton hands are a thin rectangular shape. For other hand types the width often varies between the middle and outside of the dial, where for baton hands it tends to be more consistent. Their corners may be curved or quite straight.
Breguet hands
Breguet hands are a long thin shape with rings near the ends of the hands. The width of the long thin part varies, where it might be very thin like stick hands or be more curved with the area near the middle of the dial and just above the ring being slightly wider.
Dauphine hands
Dauphine hands are a triangular faceted shape, where one side is very thin at the middle of the dial and two sides are very long with the tip of these sides pointing towards the time on the outside of the dial.
Stick hands
Stick hands are very similar to baton hands, where they're a similar consistent rectangular shape with curved/straight corners, but stick hands are thinner. You might see baton/stick hands used interchangeably when a hand is fairly thin.