How do I know what type of propellers to get for my drone and what do the specific numbers for each propeller mean?
The first step to getting the right propellers is to figure out what size propellers will fit your drone. What you can do is measure the distance from the center of the motor to the closest thing (probably the frame) that would block the propeller. Multiply that by two, and a few millimeters smaller than that is the maximum prop size/diameter. (smaller props can also work)
For example: if the center of a motor is 2.6 inches away from a frame, I would get 5'' props.
The next thing to look at is the pitch and number of blades. This is where most of the numbers come in for props. Let's use the example of 5143. the first part, 51, is the prop diameter (5.1'') and the second part is the pitch of the prop, 43, which would mean that the pitch of the prop is 4.3''. A higher pitch generally uses more power but can result in faster flying to some extent. (sometimes the prop pitch is not entirely accurate, as it depends on what the manufacturer thinks) The number of blades of the prop will be listed separately when the dimensions of the prop are listed like this.
Another way you may see prop dimensions formatted is like this: 5.1x4.3x3. That essentially says the same thing except it also includes the number of blades, which in this case, is 3. The 5.1 is 5.1'' diameter and the 4.3 is 4.3'' of pitch.
What I would recommend is to try many different types of propellers because many props that have the same measurements will perform differently.