The rhythmic note that has three beats is called a half note.

Answer;

Dotted half note

The rhythmic note that has three beats is called a dotted half note.

Explanation;

A dotted note is a music note* of any length with a small dot after its note-head. A dotted half note is equivalent to 1 half note + a quarter note, or 3 beats.  

A dotted quarter note, on the other hand is equivalent to, 1 quarter note + an eighth note: 1 1/2 beats while a dotted eighth note = 1 eighth note + a sixteenth note: 3/4 beat

A dotted half note has the same time value as a dotted half rest. A half rest lasts for two beats while a dotted half rest lasts for 3 beats.