restrictive / nonrestrictive appositives
Commas with an identifying noun beside another noun.
A restrictive appositive identifies which one and takes no comma: My sister Dana filed the brief. A nonrestrictive appositive adds a name or a note and takes commas: My sister, Dana, filed the brief when the reader already knows which sister.
Examples
UseMy brother Lee has the key.
UseMy brother, Lee, has the key. (Only one brother.)
AvoidMy brother, Lee, has the key. (If he has more than one brother and Lee is the identifier.)