• There are some encoding problems with the Spanish translations files
• The file affected is jenkins\management\Messages_es.properties

• There are several words like "configuraci\u00DBn", "informaci\u00DBn" which have an incorrect character. It should be "\u00F3" instead of "\u00DB"
• "a\u00D2adir" should be "a\u00F1adir"
• "\u2044til" should be "\u00DAtil"

Apart from that, there are two sections that are not translated (I don't know the key in the property). Here is the translation:

Configure Global Security --> Configuraci\u00F3n global de la seguridad
Secure Jenkins; define who is allowed to access/use the system. --> Seguridad en Jenkins. Define qui\u00E9n tiene acceso al sistema (autenticaci\u00F3n) y qué puede hacer (autorizaci\u00F3n)

Manage Credentials --> Gesti\u00F3n de credenciales
Create/delete/modify the credentials that can be used by Jenkins and by jobs running in Jenkins to connect to 3rd party services. -->
Crear/borrar/modificar las credenciales que pueden ser usadas por Jenkins y por las tareas que se ejecutan en \u00E9l para conectar con servicios de terceros

Thanks.