Here are some examples:
* Legitimate: lawful, rightful, conforming to the law
* Legislature: a body of lawmakers
* Legal: relating to the law
* Illegal: against the law
However, "leg" can also sometimes be used as part of a word that relates to "reading" or "selecting". This usage comes from the Latin word *lego*, meaning "to read" or "to choose".
* Legible: capable of being read easily
* Legibility: the quality of being easy to read
* Legation: a diplomatic mission
* Legacy: something handed down from the past
The specific meaning of "leg" will depend on the context of the word it's part of.