There is more to it. Our camera already has a very good reflected meter. The purpose of getting a hand held light meter would likely be that it can be an Incident meter then. The meters in cameras are reflected meters.
A reflected meter meters at the camera, aimed at subject, and reads the light reflected from the subject.
An incident meter meters at the subject (in their light), aimed at camera, and directly reads the light incident upon the subject, independent of subjects colors. This is wonderful in the studio, but metering at the subject is generally awkward out in the field.
Example: A white dress reflects a lot of light. It meters high, and a reflected meter sees that reflected light as bright, and then sets an exposure to make it be around middle gray (underexposing).
A black dress reflects little light. It meters low, and a reflected meter sees that reflected light as dim, and then sets an exposure to make it be around middle gray (overexposing).
Many subjects are a mix of "average" reflectivity, which often works OK. Exceptions don't. That is simply how reflected meters necessarily work. The meter does not know what the subject is, so result (average of any metered area) is put around middle gray (14%), not too bright, not too dark.
A Spot meter is a reflected meter, so we better know and consider the reflectivity of that spot.
An incident meter reads the actual light directly, light on the subject at the subjects location but independent of subject, and either dress likely comes out exposed about right.
The camera meter is a very good reflected meter, surely best choice in a reflected meter.
But an incident meter is more often correct and it also reads flash.
http://www.scantips.com/lights/handheld_lightmeter.html has more.