Column type TIME postgresql, returns object

I have a table that has columns that are of type TIME

I work with symfony, so what I need is for this field to be filled in a form generated with symfony, but when it is generated I get this error:

  

Type error: Return value of AppBundle \ Entity \ Department :: getHoraInicio () must be of the type string or null, object returned

I do not know what kind of data I should put in the setter:

Currently it is like this

/**
 * @return string
 */
public function getHoraInicio(): ?string
{
    return $this->horaInicio;
}