The reflexive pronoun refers back to the subject of the sentence.
 
Example:
Der Koch wäscht sich die Hände.
The chef washes his hands.

The forms of the reflexive pronoun are almost identical to the forms of the personal pronouns.
Only in the 3rd person singular and the 3rd person plural you use the pronoun 'sich' (engl. yourself).

The pronoun 'sich' is not flexed.
It does not distinguish gender or number.
It is used only in the accusative and in the dative.